W-UNiVERS/A ^105 ANGElfj> -^OF-CAllFOSto ,AttUNlVER% t! ?' ^xaaAiNiHfi? 1 j < >| |> ? ^. T s*^ S p __ which con tains the eluding themselves ovules or young seeds. and the grubs or larvae which are the young of the species. But, in addition to these workers, the hive has a queen, who is the only perfect female, or mother, and who lays the eggs from which the larvae are produced ; and it has also several drones, who are the males of the community, and fathers of the larvae. v Thus we have a colony or city, as it were, consisting of a few males, a single female, and a whole body of worker or feeder neuters. Now, a higher plant, like a cherry-tree (to take a particular example), is just such a colony or joint community. The leaves, each of which is a distinct and almost self-supporting individual, are its workers and feeders. Like the worker bees, too, the leaves are neuters neither true 78 THE STORY OF THE PLANTS. males nor true females. They feed and lay by, and from them new leaves are continually pro- duced in the buds and at the ends of branches. This is called the sexless method of reproduction, and it is essentially similar to the way in which the single-celled plant or the simple animal di- vides itself sexlessly into two or more little plant- lets or animals. But, in addition to this sexless w ? ay, the plant also at certain times produces other sorts of leaves which are sexual individuals, and these we call, in the lump, flowers. But flo\vers are not all alike throughout. They con- sist of certain male individuals, the stamens, which answer to the drones, and of certain female indi- viduals, the pistils or carpels, which answer to the queen or mother bee, and produce the ovules or little eggs of the family. A cherry-tree is thus a plant-hive or colony, consisting for the most part of workers or leaves, but also at certain times of year producing male and female members, whose business it is to found fresh swarms, as it were to produce the seeds which are the basis and foundation of new colonies. There is of course one great difference be- tween a hive and a plant, and that is that in the hive the individuals are separate and distinct, while in the plant they are combined on a single stem, which serves to join them. In this respect plants are more like a branch of coral, which con- sists of a number of distinct animals or polypes, united by a core of stony material, and a living mass of connecting matter. Yet the difference between the leaves and the bees is not so great as at first sight appears ; for though each leaf does not as a rule live separately, it is often capable of doing so if occasion arises. A single HOW PLANTS MARRY. 79 leaf of stonecrop, separated from the parent plant, will root itself and grow into a fresh colony ; and in some plants, like begonias, a single fragment of a leaf, if placed on wet soil, is capable of growing out into a new individual. In other cases small leaves drop off from a plant as bulbils, and root and grow ; while in others, again, young plants sprout out from the edges of old leaves to form new colonies. In short, though the leaf is not usually a distinct plant, it sometimes is, and it can often become one ; it frequently gives rise in a sexless way to fresh plant colonies. A graver difficulty is this: the plant differs from the hive in being more closely connected and subordinated in its parts the stem and root (which bind and unite it), bringing water and nitrogenous matter, while the leaves elaborate the starch and protoplasm and other chief food-stuffs. Even this difference, however, is less grave than it seems, if we remember that the queen bee and the larvae are similarly depend- ent upon the workers for food and protection. A plant, in short, is a colony of various forms of leaves, very closely united together for mutual service, and very much specialised in various ways among themselves for particular functions. And now we are in a position to know what work the flower has to do in the community. It is a collection of special and peculiar leaves, told off to act as fathers and mothers to the seeds, whence are to be born future plant swarms or future colonies. A flower, in its simplest form, consists of a single stamen or a single carpel that is to say, of one leaf or leaf-like organ, told off for the pro- 8o THE STORY OF THE PLANTS. duction of pollen ; or of one leaf or leaf-like or- gan, told off for the production of young seeds or ovules. Flowers as simple as that do actually occur, but more often a flower is much more com- plex, consisting of several stamens and several carpels, as well as of other protective or attract- ive leaves, often highly coloured and conspicu- ous, which surround or envelop these essential organs. The most familiar flowers, as we actually know them, are of this last more complex type ; each comprises in itself several male and several female individuals. The male individuals are stamens, each of which generally consists of two little pollen- bags, called the anthers, and a rather slender stalk or support, known as the filament. The female individuals are carpels, each of w r hich generally consists of a sort of sack or folded leaf, enclosing one or more tiny seeds or ovules. But that is not at all what you mean by a flower ! No ; certainly not ; and half the flowers you meet in a morning's walk you do not take for flowers at all, and pass by unrecognised. Such are the green or inconspicuous blossoms of the grasses, nettles, oaks, and sedges, as well as those of the pines, the dog's mercury, the spurge, and the hazel. What you mean most by a flower is a mass of red or yellow petals, conspicuously arranged about the true floral organs. The pet- als form, in point of fact, the popular notion of a flower though from the point of view of science they are comparatively unimportant, and are commonly spoken of (with the calyx) as "the floral envelopes." It is the stamens and pistils (or carpels) that are the true flowers ; they do the mass of the real work ; and an enormous number HOW PLANTS MARRY. 8 1 of flowers possess these organs alone, without any conspicuous petals or other coloured sur- faces. However, if you take a pretty garden flower (say a scarlet geranium) as a typical example, and begin to examine it from the centre outward (which is the truest way), you will find it consists of the following parts, in the following or- der: In the very cen- tre of all comes the pistil, consisting of one or more carpels, and containing the embryo seeds or ovules (see Fig. 15). Outside this part, and next in order, come the stamens, which are most of- ten three or six in one great group of flowering plants (the lilies), and five, ten, or more in the other (the roses and buttercups). The FlG ^ 6> _ Grains of pollen) veiy much Stamens produce magnified, sending out pollen-tubes. grains of pollen which somehow or other, either by means of the wind, or of insects, or of movements on the part of the plant itself, are sooner or later applied to the sensitive surface or stigma of the pistil. As 6 82 THE STORY OF THE PLANTS. soon as a pollen-grain reaches the surface of the stigma, it is held there by a sticky secretion, and instantly begins to send out what is called ^pollen- tube (Fig. 1 6). This pollen-tube makes its way down the long stem or style which joins the stigma to the ovary, and there comes in contact with the undeveloped ovules. The ovules would not swell and grow into seeds of themselves; but the mo- ment the pollen-tube reaches them, they quicken FlG. 17. Flower of a shrubbery plant, Weigelia, with the petals united into single corolla. I, entire flower ; II, the same, with part of the corolla cut away ; III and IV, a stamen : k, calyx ; d, corolla ; .r, stamen ; a, anther of the stamen ; g and , parts of the pistil. into life, and begin to develop into fertile seeds. Unfertilised ovules wither away or come to noth- ing, but fertilisation by pollen makes them de- velop at once into new plant colonies. Outside these essetitial organs, as botanists call them, however, come, in handsome garden flowers, two other sets of organs, more leaf-like in appear- ance, but often brightly or conspicuously col- HOW PLANTS MARRY. 83 cured. The first of these sets of organs, going still from within outward, is called \.\\z petals, or, collectively, the corolla. Sometimes, as in the dog-rose or the buttercup, the corolla consists of five separate petals ; sometimes, as in the harebell and the gentian, it has five points, or lobes, united at the base into a single piece (Fig. 17). Last of all, outside the corolla again comes another row or layer, called the calyx, which sometimes con- sists of five separate leaves or sepals, as in the dog-rose and the buttercup, but sometimes has five points, welded at the base into one piece, as in red campion and convolvulus. It is these last comparatively unessential but very conspicuous parts that most people think of when they say " a flower." What is their use? Well, they are not essen- tial, like the pistil and stamens, because many flowers, perhaps even most flowers, do without them altogether. But they are very useful for all that, as we may easily guess, because they are found in almost all the most advanced and devel- oped flowers. The use of the corolla, with its bril- liantly coloured petals, is to attract insects to the flowers and induce them to carry pollen from plant to plant. That is why they are painted red and blue and yellow; they are there as advertise- ments to tell the bee or butterfly, " Here you can get good honey." The use of the calyx is usually to cover up the flower in the bud, to keep it safe from cold, and to protect it from the attacks of insect enemies, who often try to break through and steal the half-developed pollen in the bags of the stamens before it is ripe and ready for fer- tilising. These are the chief uses of the calyx or 84 THE STORY OF THE PLANTS. outer cup of the flower ; but, as we shall see here- after, it serves many other useful purposes from time to time in various kinds of flowers. In the fuchsia, for example, it is quite as brilliantly col- oured as the petals of the corolla, and supple- ments them in the work of attracting insects. In the winter cherry or Cape gooseberry it forms a brilliant outer envelope or covering for the fruit, which the French call " cerise en chemise" or "cherry in its nightdress." Other uses of both calyx and corolla will come out by and by, as we proceed to examine individual instances. " But why," you may ask, " do the plants want to get pollen carried from plant to plant ? Why can't each flower fertilise itself by letting its pol- len fall upon its own pistil?" Well, the question is a natural one; and, indeed, many flowers do actually so fertilise themselves with their own pollen. But such flowers are almost always poor and degenerate kinds, the unsuccessful in the race, the outcasts and street arabs of plant civili- sation. All the higher, nobler, and more domi- nant plants the plants that have carved out for themselves great careers in the world, and that occupy the best posts in nature have invented some mode or other of cross-fertilisation, as it is called, that is to say some plan by which the pol- len of one plant or flower fertilises the pistil of another. What does this mean ? Well, regarding the plant as a colony, you will see at once that the stamens and pistil of the same blossom stand to one another somewhat in the relation of brothers and sisters, while those of different flowers on the same plant may be regarded at least in the light of first cousins. Now the very same thing that HOW PLANTS MARRY. 85 makes sex and marriage desirable, makes close intermarriage of blood relations undesirable. " Marrying in and in," as it is called, tends to produce weak and feeble offspring, while " an in- fusion of fresh blood " tends to make both plants and animals stronger and more vigorous. Hence, if any habit chanced to arise in plants which fa- voured or rendered easier such cross-fertilisation, it would result in stronger and more vigorous young, and would therefore be fixed by natural selection. The actual consequence is that in the world of plants, as we see it to-day, every great dominant or successful race has invented some means of cross-fertilisation, either by the agency of wind or of insects, while only the mis- erable riff-raff and outcasts of plant-life still ad- here to the old and bad method of fertilisation by means of the pollen of their own flowers. We are now in a position to understand the main principles which govern the marriage cus- toms of plants ; we will proceed in the next chap- ter to consider in detail how these principles work out in particular instances. But first we must sum up what we have learnt in this chapter. Plants marry and are given in marriage. The very lowest plants, indeed, are sexless, but in the higher there are well-marked distinctions of male and female. An intermediate stage exists in cer- tain thread-like pond-weeds, where marriage or intermixture takes place between two adjacent cells, neither of which is male or female. The higher plants, however, are really communities or colonies, of which the leaves are the workers, and the various parts of the flower the males and females. The central part of the flower, known 86 THE STORY OF THE PLANTS. as the pistil, is the female individual ; it produces ovules, or young seeds, which, however, cannot grow and swell without the quickening aid of pol- len. The next row in the flower, known as the stamens, contains the male individuals; they pro- duce pollen, which lights on the sensitive surface of the pistil, sends out tubes of very active living matter, and quickens or impregnates the ovules in the pistil. Besides these necessary organs flow- ers have often two other sets of parts. The co- rolla, which is made up of petals, united or dis- tinct, is usually brightly coloured, and acts as an advertisement or allurement to the insects; it oc- curs chiefly in insect-fertilised flowers, and gener- ally implies the presence of honey. The calyx or outer cup, which is made up of sepals, distinct or united, acts mainly as a protective covering. Plants can fertilise themselves if necessary, but in all the highest and most successful plants some form or other of cross-fertilisation has become almost universal. Self-fertilisation goes down the hill ; cross-fertilisation is the road to success and vigour. CHAPTER VII. VARIOUS MARRIAGE CUSTOMS. THE simplest and earliest flowering plants had probably only three sets of organs leaves, stamens, and pistils workers, males, and females. Their flowers consisted at best of the necessary organs, enclosed, perhaps, in a few protective sheathing leaves, rather smaller than the rest, the forerunners of a calyx. How, then, did mod- VARIOUS MARRIAGE CUbfOMS. 87' ern flowers come to get at last their brilliant corollas ? We must remember that anything which made flying insects visit plants would be of use to the flowers, as promoting cross-fertilisation. Now, as far as we can see at present, before flying insects were evolved in the animal world, there could have been no such things as bright-hued blossoms in the vegetable kingdom. But insects must very- early have gone about eating pollen on plants, as they do to this day in many instances ; and though in itself this would be a loss to the plant, yet plants have often found it well worth their while to pay blackmail to insects in return for some benefit incidentally conferred upon them. Again, as the insects flew from plant to plant, they would be sure to carry pollen on their heads and legs ; and they would rub off this pollen on the sticky stigma of the next flower they visited, which would make them on the whole useful and profit- able visitors. So the plants, finding the good cross-fertilisation did them, began in time to bribe the insects by producing honey in the neighbour- hood of their pistils and stamens, and also to at- tract their eyes from afar by means of those allur- ing and brilliantly-coloured advertisements which we call petals. I don't mean, of course, that the plants knew they were doing all this ; they were unconscious agents. Whenever any variation in the right di- rection occurred by chance, natural selection im- mediately favoured it, so that in the end it comes almost to the same thing as if the plant deliber- ately intended to allure the insect ; and for brev- ity's sake I shall often so word things. How did the plant first come to develop such 88 THE STORY OF THE PLANTS. bright-hued petals ? I think in this way. Most early types of flowers have a great many stamens apiece, and these stamens are so extremely nu- merous that one or two of them might readily be spared for any other purpose the plant found use- ful. Gradually, as botanists imagine, an outer row of these stamens got flattened out into a form like foliage leaves, only without any ribs or veins to speak of, and developed bright colours to at- tract the insects. Such a flattened and gaily- decked stamen, with no pollen-bearing bag, is what w r e call a petal. It is usually expanded, thin, and spongy, and it is admirably adapted for the display of bright colours. We have still certain flow r ers among us which show us pretty clearly how this change took place. The common white water-lily is one of them. In the centre of the blossom, in that beautiful plant, we find a large pistil and numerous stamens ot the ordinary sort, with round stalks or filaments, and yellow pollen-bags hanging out at their ends. Then, as we move forward, we find the filaments or stalks growing flatter and broader, and the pollen-bags gradually less and less perfect. Next we come to a few very flat and broad stamens, looking just like petals, but with two empty poU len-bags, or sometimes only one, stuck awk- wardly on their edges. Last of all we arrive at true petals without a trace in any way of pollen- bags. I believe the water-lily preserves for us still some memory of the plan by which petals were first invented. Such relics of old conditions are common both in plants and animals; they help us greatly to reconstruct the history of the path by which the various kinds have reached their present perfection. VARIOUS MARRIAGE CUSTOMS. 89 Even in our own day, in plants where stamens are numerous, they often tend to develop into petals, especially when growing in very rich soil, or under cultivation. This is what we call " doub- ling " a flower. In the double rose, for example, the extra petals are produced from the stamens of the interior, and if you examine them closely you will see that they often show every possible grada- tion and intermediate stage, from the perfect sta- men to the perfect petal. The same thing read- ily happens with buttercups, poppies, and many other flowers. We may take it for granted, then, that petals are, in essence, a single outer row ot stamens, flattened and coloured, and set apart by the plant to advertise its honey to insects, and so induce them to visit and fertilise it. In the largest and most familiar group of flow- ering plants, to which almost all the best-knoivn kinds belong, the original number of petals seems to have been five; and we will take this number as regular for the present, explaining separately those cases where it is exceeded or diminished. The common ancestor of all these plants, we may conclude, had all its parts in rows of five. Thus it had five, ten, or fifteen carpels in its pistil that is to say, one, two, or three rows of five carpels each ; it had five, ten, or fifteen stamens, it had rive or ten petals, and it had a calyx, outside all, of five sepals. We will now proceed to examine in detail some of the many curious marriage cus- toms which have arisen among the group of plants that started with this ground-plan. One great family of plants which early divided itself from this great central stock is the family of the buttercups. Our common English bulbous pO THE STORY OF THE PLANTS. buttercup is one of its best-known members. It is yellow in colour, a point which is common to most early and simple flowers, because the sta- mens are generally yellow, and w r hen they devel- oped into petals they naturally retained at first their original colouring. Only later and for vari- ous special reasons did certain higher flowers come by degrees to be white, pink, red, blue, purple, or variegated. There is some reason to believe, indeed, that the various other colours were developed one after the other in the order here named, and to the present day all the sim- plest families of flowers remain chiefly yellow, as do the simpler and earlier members of more ad- vanced families. The common bulbous buttercup is thus pre- vailingly yellow, because it is an early and simple type of flower. It consists of four distinct and successive layers, or whorls of organs. Outside all comes a calyx of five sepals, which cover the flower in the bud, but are hardly noticeable in the open blossom. They also serve to keep off ants and other creeping insects, for which purpose they are turned back on the stem, and are covered with small hairs. " But I thought the plant wanted to attract insects," you will say. Yes, the right kind of insects, the flying types, which go from one flower to another of the same sort, and so promote due fertilisation. Flying insects, at- tracted by colour and shape of petals, keep to one brand of honey at a time ; they never mix their liquors. But ants are drawn on by the smell of honey only ; they crawl up one stem after an- other indiscriminately, and steal the nectar which the plant intends for its regular winged visitors. Even if they do occasionally fertilise a flower, it VARIOUS MARRIAGE CUSTOMS. 91 will probably be with pollen of another kind, so that the result will be, not a perfect plant, but a miserable hybrid, ill adapted for any conditions. Hence plants usually possess advanced devices for keeping off ants and other climbing thieves from their precious honey. Hairs on the stalk and calyx are enough to secure this object in the meadow buttercup, which has a tall stem, and therefore is not so easily climbed ; for the hairs, small as they look to us, prove to the ant a per- fect forest of underwood. But in the early bulbous buttercup, which has a shorter stem, and the smell of whose honey is therefore more allur- ing to the groundling ant, this device is not alone sufficient ; so the calyx on opening turns down its separate sepals close against the stem in such a way as to form a sort of lobster-pot, out of which the creeping insect can never extricate himself. Inside the calyx-layer of five sepals comes next the corolla-layer of five petals. These petals, as we saw, are the attractive business advertise- ment of the flower ; they contain at the base of each a tiny honey-gland or nectary, which is cov- ered by a scale or small inner petal, so to speak, to protect it from the attacks of thievish insects. But when the bee or other proper fertilising agent arrives at the flower, he lights on the set of carpels in the very centre of the blossom, and proceeds to go straight for the little store of honey. As he does so, he turns gradually round all qver the carpels, and dusts himself with pollen from the ripe sta- mens. And now we must notice another curious device for ensuring cross-fertilisation in many flowers. In the bulbous buttercup the stamens and carpels do not come to maturity together ; 92 THE STORY OF THE PLANTS. the stamens ripen first, and after them the carpels. How does this ensure cross-fertilisa- tion ? Why, if the bee comes to a flower in the first or male stage, in which the stamens are at their full, and discharging pollen, the sensitive surfaces or stigmas of the carpels will yet be immature, so that he cannot fertilise them with pollen from their own blossom. He can only collect there, without disbursing anything. But as soon as he comes to a flower in its second or female stage, with the carpels ripe, and their sensitive surfaces sticky, he will rub off some of the pollen he has thus collected, and so cross- fertilise the flower he is visiting. Each buttercup thus goes through two stages. First, its stamens ripen from without inward, till all have shed their pollen and withered. Then the carpels ripen in the same order, till all have been fertilised by the appropriate insect. Each carpel here contains a single seed, which begins to swell as soon as the ovary is impregnated. We may take it that some such flower as that of the bulbous buttercup represents the original ancestor of all the buttercup group, from which other kinds have varied in many .directions. Omitting for the present all questions as to the fruit and seed, which we must examine at length in a later chapter, I will now proceed briefly to describe a few of these variations in the butter- cup family. The true buttercups themselves are distin- guished from all other members of the group by having a tiny scale over the nectary or honey- gland at the base of the petal, or at least by having the nectary itself as a visible pit or small depression. Almost all of them are yellow, though VARIOUS MARRIAGE CUSTOMS. 93 in other respects they differ from one another, as in the shape of the leaves, or in the way in which the sepals are turned back to form a protection against insects. One of the yellow buttercups, too, commonly called the lesser celandine, has varied from the rest of the race in a peculiar : fashion ; for it has only three sepals, instead of five, according to the usual pattern ; while, as if to make up for this loss in one part, it has eight petals instead of five in its corolla. I merely mention this fact to show how many small changes occur in different flowers, even within the limits of the same family. And though most of the true buttercups are yellow, a few are white, such as our own water-crowfoot, and the alpine butter- cup called bachelors' buttons; while still fewer are red, like the turban ranunculus of our spring gardens. But besides the true buttercups, we have also a vast group of buttercup-like plants, descend- ants of the same primitive five-petalled ances- tor, and regarded as members of the buttercup order. In these we can trace some curious gra- dations. The little winter aconite of our gar- dens has this peculiarity : the petal and nectary have grown into a sort of tubular honeycup, much more attractive to greedy insects than the simple scale-bearing petal of the buttercups. But as this involves loss of expanded colour-surface, the winter aconite has made up for the deficiency by colour- ing its calyx a brilliant yellow, so as to resemble* a corolla. Several other buttercup-like plants have even lost their petals altogether, and make coloured sepals do duty in their place. The marsh-marigold, for instance, is one of these ; what look like petals in it are really very brilliant 94 THE STORY OF THE PLANTS. yellow sepals. Moreover, as the marsh-marigold is such a large and handsome flower, it easily at- ' tracts insects in early spring ; and this has enabled it to effect an economy in the matter of its carpels or female organs. In the buttercups, we saw, these were very numerous, and each contained only one seed; in the marsh-marigold, on the other hand, they are reduced to five or ten, but each contains a large number of seeds. This arrangement enables a few acts of fertilisation to suffice for the whole flower. You will there- fore find as a rule that advanced types of flowers have very few r carpels sometimes only one and that when they are more numerous they are often combined into a single ovary, with one sensitive surface, so that one fertilisation is enough for the whole of them. Three familiar but highly-advanced members of the buttercup group will serve to show the im- mense changes effected in this respect by special insect fertilisation. They are the columbine, the larkspur, and the monkshood. In the simple but- tercups, the honey, we saw, was easily acces- sible to many small insects; but in the winter aconite it was made more secure by being kept, as it were, in a sort of deep jar ; and in these high- est of the family it is still further hidden away, in special nooks and recesses, like vases or pitchers, so as to be only procurable by bees and butter- flies. These higher insects, on the other hand, are the safest fertilisers, because they have legs and a proboscis exactly adapted to the work they are meant for; and they have also as a rule a taste for red, blue, and purple flowers, rather than for simple white or yellow ones. Hence iiie blossoms that specially lay themselves out VARIOUS MARRIAGE CUSTOMS. 95 for the higher insects are almost always blue or purple. Columbine still retains the original five sepals and five petals of its buttercup ancestor. But the sepals here are blue or purple, and are displayed between the petals in a most curious manner, so as to help in the coloured advertisement of the honey. The petals, on the other hand, are turned into long spurred horns, each with a big drop of honey in its furthest recess, securely placed where only an insect with a very long proboscis has any chance of reaching it. Within these two rows come the numerous stamens; and within them again a set of five carpels, each many-seeded. The columbine is so secure of getting its seed set by bees or butterflies that it is able to dispense with the extra carpels. Larkspur carries the same devices one step further. Here, there are five sepals, coloured blue, and prolonged into a spur at the base, which cov- ers the nectaries. Why this outer covering ? Well, in columbine, thievish insects like wasps often eat through the base of the spurred sepals and steal the honey, without benefiting the plant in any way, as they don't come near the stamens and carpels. Larkspur provides against that evil chance by covering its honey with two protective coats ; for within the spur of the sepals lies a spurred nectary made up of the petals. The petals themselves are reduced to two, because the sepals are coloured, and do all the attractive duty; and besides, even these two petals are combined into one, as a fur- ther economy. But the arrangement of the flower is so admirable for ensuring fertilisation that the plant is able still further to dispense with unneces- sary parts; so many larkspurs have only a single 96 THE STORY OF THE PLANTS. many-seeded carpel. Such reductions in the num- bers of parts are always a sign of high develop- ment. Where the devices for effecting the work are poor, many servants are necessary ; where labour-saving improvements have been largely in- troduced, a very few will do the same work, and do it better. Monkshood, again, is another example of the same tendency. Here, the one-sidedness which we saw in the larkspur reaches a still more ad- vanced development. The upper sepal is formed into a brilliant blue hood, and it covers two curi- ously shaped petals, which contain an abundant store of honey. This arrangement is so splendid for fertilisation that the plant is able largely to reduce its number of stamens; and though it has three carpels, these are combined at the base, thus showing the first step towards a united ovary. I have treated the single family of the butter- cups at some length, because I wished to show you what sort of variations on a single plan were common in nature. "We see here a family, built all on one scheme, but altering its architecture and decoration in the most singular degree in its different members. The simplest kinds are cir- cular, symmetrical, orderly, and yellow; the high- est are irregular, somewhat strangely shaped, and blue or purple. This is the general line of evolu- tion in flowers. They begin like the buttercup ; they end like the monkshood. Familiar instances of round or radial flowers, consisting of separate petals, are the dog-rose, the poppy, the mallow, and the herb-Robert or wild geranium. Most of these have five sepals and five petals; but in the poppy the petals are usual- VARIOUS MARRIAGE CUSTOMS. 97 ly reduced to four, and the sepals to two. Again, a good instance of flowers with separate petals which have become one-sided or irregular, instead of circularly symmetrical, is afforded us by the peaflowers, which include the pea, the bean, the sweet-pea, the laburnum, the broom, the gorse, the vetch, and the lupine. This familiar family,, known to botanists as the papilionaceous or but- terfly-like order (I trouble you with as few long names as I can, so you must forgive one or two occasionally), is one of the largest in the world, and includes a vast number of the most useful and also of the most ornamental species. The structure of the flower, which is very similar in them all, can be easily studied in the broom or the sweet-pea, plants procurable by everybody. There are still five petals, though two of them are united to form a lower portion of the flower, known as the keel; then two others at the side are called the wings; while a broad and often handsomely coloured advertisement-petal at the top of all is called the standard. The sepals are often combined into a single calyx-piece, though as a rule the calyx still retains five lobes or teeth, a reminiscence of the time when it consisted of five distinct and separate sepals. The stamens are welded together into a sort of long tube ; and the pistil is reduced to a single carpel or pod, containing a few big seeds, very familiar to most of us in the case of the pea, the bean, and the scarlet-runner. This shape of flower has proved so successful in the struggle for life that papil- ionaceous plants are now common everywhere, while hundreds of different kinds are known in various countries. Yet closely as the peaflowers resemble one 7 98 THE STORY OF THE PLANTS. another in general aspect, they have still among themselves a curious variety of marriage customs. I will mention two only. In gorse, a flower which everybody can easily examine, the wings have two little knobs at the sides for the bee to alight upon. As he does so, the corolla springs open elastically, and dusts him all over with the fer- tilising pollen. But once it has burst, it remains permanently open, the keel hanging down in a woe-begone way, so that no bee troubles himself again to visit it. This saves time for the bees, and enables them quicker to fertilise the remain- ing flowers; for when they see a gorse-blossom " sprung," as we call it, they recognise at once that it has already been fertilised, and they know they can get no food by going there. In the lupine, on the other hand, and in the common little English birdsfoot-trefoil, the keel is sharp at the point, and the pollen is shed into it before the flower fully opens. When a bee lights on the knobs at the side, he depresses the keel, and the pollen is pumped out against his breast in the most beautiful manner. I hope my readers will try some of these experiments in summer for themselves, and satisfy their own minds whether these things are so. So far, we have dealt mainly with flowers in which the petals are all still distinct and separate. But in a great many plants, the petals have grown together, so as to form a single piece, a " tubular corolla," as we call it. This arrangement is very well seen in the harebell, the Canterbury bell, the heath, and the convolvulus. How did such an arrangement arise ? Well, in many flowers even with distinct petals there is a slight tendency for VARIOUS MARRIAGE CUSTOMS. 99 adjacent parts to adhere at the base; and in cer tain blossoms this tendency to adhesion must have benefited the plant, because it would allow the proper fertilising insect to get in with ease, and to find his way at once to the stamens and stigma or sensitive surface. The consequence is that the majority of the higher plants have now corollas in a single piece ; and most of these are also coloured red, blue, or purple. Still, even now many of them retain marks of the original five petals. For instance, the harebell has the edge of the corolla vandyked into five marked lobes; while in the primrose, only the base of the corolla forms a tube or united pipe, the outer part being composed of five deeply-cut lobes, reminiscences of the five original petals. Indeed, some relations of the primrose, such as the pim- pernel and the woodland loose-strife, have the petals only slightly united at the base, and would hardly be noticed by a casual observer as possess- ing a tubular corolla. There is one marriage custom of the primrose, however, so very interesting that we must not pass it by even in so brief a survey. Most chil- dren are aware that we have in our woods two kinds of primroses, w T hich they know respectively as pin-eyed and thrum-eyed. In the pin-eyed form (Fig. 18), only the little round stigma is visible at the top of the pipe, while the stamens, here joined with the corolla-tube, hang out like little bags half-way down the neck of it. In the thrum-eyed form (Fig. 19), on the other hand, only the stamens are visible at the top of the tube, while the stigma, erected on a much shorter style, occupies just the same place in the tube that the stamens occupied in the sister blossom. THE STORY OF THE PLANTS. Now, each primrose plant bears only one form of flower. Therefore, if a bee begins visiting a thrum-eyed form, he will collect pollen on his proboscis at the very base only ; and as long ar he goes on visiting thrum-eyed flowers, he car only collect, without getting rid of any grains on FlG. 18. Pin-eyed primrose, cut open so as to show the arrangement of the stamens and stigma. FlG. 19. Thrum-eyed prim- rose, cut open so as to show stamens and stigma. the deep-set stigmas. But when he flies away to a pin-eyed blossom, the part of his proboscis which collected pollen before will now be op- posite the stigma, and will fertilise it ; while at the same time he will be gathering fresh pollen below, to be rubbed off on the sensitive surface of a short-styled flower in due season. VARIOUS MARRIAGE CUSTOMS. IOI Thus every pin-eyed blossom must always be fer- tilised by a thrum-eyed, and every thrum-eyed by a pin-eyed neighbour. This is one of the most ingenious arrangements known for cross-fertilisa- tion. Much as I should like to dwell further on these interesting cases, I must hurry on to com- plete our rapid survey of a great subject. Flow- ers like the harebell and the primrose are tubular but regular. Other flowers with a tubular corolla go yet a step further and are irregular also. This irregularity, like that of the monkshood, secures for them in the end greater certainty of fertilisa- tion. Two well-known groups of this sort are the sages, on the one hand, and the fox-gloves, monkey-plants, and snap-dragons on the other. I shall mention only one instance of special de- vices for cross-fertilisation in these groups, that of the various sages, beautifully seen in the large blue salvias of our gardens. In this plant there are only two stamens, though most of the group to which it belongs have four, because the ex- cellent arrangements for fertilisation make this . single pair a great deal more effective than the thirty or forty required by the common buttercup. For the stamens are delicately poised on a sort of lever, so that the moment the bee enters the flower, they descend and embrace him, as if by magic. While the stamens alone are ripe, this continues to happen with each flower he visits; but when he goes away to an older blossom, he finds the stigma ripe, and bending over into the spot previously occupied by the stamens. You can try this experiment very easily for yourself by putting a straw or bent of grass down the 102 THE STORY OF THE PLANTS. tube of a garden salvia, when the stamens will at once bend down and embrace it in the way I have mentioned. You must not suppose, however, that all flow- ers are fertilised by bees and butterflies. Many plants lay themselves out for quite different vis- itors. Take for example our common English figwort. This is a curious, lurid-looking, reddish- brown blossom, shaped somewhat like a helmet, and it is fertilised almost exclusively by wasps. Its shape and size exactly adapt it for a wasp's head; and it blooms at the time of year when wasps are numerous. Now wasps, as you know, are carnivorous and omnivorous creatures ; so the figwort, to attract them, looks as meaty as it can, and has an odour not unlike that of decaying mutton. Certain tropical flowers again attract carrion-flies, and these have big blossoms that .ook like decomposing meat, and smell disgust- ingly. A South African flower of this sort, the Stapelia, is sometimes cultivated as a curiosity in greenhouses. I have already remarked on the white flowers which open at night, and attract the moths of twilight ; while others again lay them- selves out to be fertilised by midges, beetles, and other insect riff-raff. Most of these have the honey displayed on wide open discs, where it can be sipped by insects with hardly any proboscis. In our latitudes it is only insects that so act as fertilisers ; but in the tropics the work of fer- tilisation is often performed by birds, such as humming-birds, sun-birds, and brush-tongued lories. Many of the most brilliant and beautiful among the bell-shaped tropical flowers have been specially developed to suit the tastes and habits VARIOUS MARRIAGE CUSTOMS. 103 of these comparatively large and powerful ferti- lisers. The tongues of all, but especially of the humming-birds, are admirably adapted for suck- ing honey from flowers, as they are long and tubular, sometimes forked at the tip, and often hairy so as to lick up both honey and insects. The length of the beak and tongue varies to a great extent in accordance with the depth of the tube in the flowers they fertilise. Bird and flower, in other words, have each been developed to suit one another. The same sort of correspondence may often be observed between insects and flowers developed side by side for mutual convenience. One more point I should like to touch upon before I pass away from this part of the subject; and that is the lines or spots so often found on the petals of highly developed flowers. These for the most part act as honey-guides, to lead the bee or other fertilising insect direct to the nectar. A very good case of this may be seen in an Indian plant which is found in every English cottage garden that is to say the so-called nasturtium. This blossom can only be fertilised by humble-bees and humming-bird hawk-moths, no other insect in England at least having a proboscis long enough to reach the bottom of the very deep spur which holds the honey. Now, humming-bird hawk- moths do not light on a flower, but hover lightly poised on their quivering wings in front of it. So all the arrangements of the flower are strictly set forth in accordance with the insect's habit. The calyx consists of five sepals with a very long spur, the end of which, as you can find out by biting it, is full of honey. Then come five petals, not, how- ever, all alike, but divided into two distinct sets, 104 THE STORY OF THE PLANTS. an upper pair and a lower triplet. The upper pair are broad and deeply-lined with dark veins, which all converge about the mouth of the spur, and so show the inquiring insect exactly where to go in search of honey. The lower three, on the other hand, have no lines or marks, but possess a curi- ous sort of fence running right across their face, intended to prevent other flying insects from alighting and rifling the flower without fertilising the ovary. This flower, too, has two successive stages ; it opens male, with stamens only, which bend upward towards the insect ; later, it becomes female, the stigma opens and becomes forked, and bends down so as to occupy the very same place previously occupied by the ripe stamens. A great many well-known flowers have such lines as honey-guides. If I have succeeded so far in interesting you in the subject, you will find it a pleasant task to hunt them out for yourself in the violet, the scarlet geranium, the spotted orchid, and the tiger lily. So far I have dealt only with the marriage ar- rangements of those plants which are fertilised by insects or birds, and \vhich belong to the great group of flowering plants descended from an early common ancestor with five petals. We must next deal briefly with the marriage customs of the in- sect-fertilised class among the other great group whose ancestor started with but three petals ; and after that we must go on to the other mode of fertilisation by means of the wind or of self-im- pregnation. This chapter has consisted so much of special cases that I do not think it stands in the same need of a summary as all its predecessors. MORE MARRIAGE CUSTOMS. 105 CHAPTER VIII. MORE MARRIAGE CUSTOMS. ALMOST all the flowering plants with which most people are familiar all, indeed, save the pines and other conifers belong to one or other of two great groups or alliances, each remotely descended from a common ancestor. The flow- ers we have hitherto been considering are entirely those which belong to one of these two groups the group which started with rows of five, having five sepals, five petals, five or ten stamens, and five or ten carpels. In several cases, certain of these rows have been simplified or reduced in number ; but almost always we can see to the x end some trace of the original fivefold arrange- ment. This fivefold arrangement is very con- spicuous in all the stonecrops, and it may also be well noticed in wild geraniums, and less well in the strawberry, the dog-rose, and the cinquefoil. In the present chapter, however, I propose to go on to sundry flowers of the other great group which has its parts in rows of three, and to show how they have been affected by insect visits. This will give us a clearer view of the whole subject, while it will also form a general intro- duction to systematic botany for those of my readers who may be induced by this book to carry their studies in this direction further. Before proceeding, however, there is one little point I should like to note about the fivefold flowers, which we shall find much more common in the threefold, and among the wind-fertilised species. This is the separation of the sexes in 106 THE STORY OF THE PLANTS. different blossoms or even on separate plants. All the flowers we have so far considered have contained both male and female portions have been made up of stamens and carpels united to- gether in the self-same blossom. But many of them, as you will recollect, have not been actively both male and female at the same moment. The stamens ripened first, the sensitive surface of the carpels afterwards ; and this, as we saw, tended to promote cross-fertilisation. But if in any spe- cies all the stamens in certain flowers were to be suppressed or undeveloped, while in other flowers the same thing happened to the carpels, self- fertilisation would become an absolute impossi- bility, and every blossom would necessarily be impregnated from the pollen of a neighbour. Natural selection has accordingly favoured such an arrangement in a considerable number of thr higher plants. In such cases some of the flowers consist of stamens only, with no carpels ; while others consist of carpels alone, with no stamens. But as all are descended from ancestors which had both organs combined in the same flower, remnants of the stamens often exist in the female flowers as naked filaments or barren threads, while remnants of the carpels equally exist in the male flowers as central knobs without seeds or ovules. The beautiful begonias, so much cultivated in conservatories, give us an excellent example of such single-sex flowers. In these plants the males and females are extremely different The male flower has four coloured and petal-like sepals, surrounding a number of central stamens. The female flower has five coloured and petal-like sepals, surrounding a group of daintily-twisted MORE MARRIAGE CUSTOMS. 107 central stigmas, while at the base of the blossom is a large triangular ovary, containing the young seeds or ovules. Usually the flowers grow in little bunches of three, each bunch consisting of two males and one female. In the pumpkins, cucumbers, and melons, separate male and female flowers also exist on the same plant. The females here may be easily recognised by having an ovary or small unde- veloped fruit at the back of the blossom, which you can cut across so as to show the young seeds or ovules within it. As the proper insects for fer- tilising cucumbers and melons do not live in Eng- land, gardeners usually impregnate the female flowers by bringing pollen from the males to them with a camel's-hair brush. This process is commonly known as " setting " the melons. Many .other garden flowers have separate male and fe- male blossoms, which the beginner can easily rec- ognise for himself if he takes the trouble to look for them. In the instances we have hitherto considered, the male and female blossoms live on the same plant. But the best cross-fertilisation of all is that which is secured where the fathers and mothers belong to totally distinct plants, a plan for facilitating which we have already seen in the common primrose. Well, now, if any species took to producing all male flowers on one plant, and all females on another, this great end would be- come absolutely certain, for every blossom would then always be fertilised by the pollen brought from a distinct plant. Many such instances have accordingly been produced in the world around us by natural selection. Only, the two kinds of plants must always grow in one another's neigh- 108 THE STORY OF THE PLANTS. bourhood. Hemp, for example, is a case of a plant where such an arrangement already exists; some plants are male only, while some are female. Mistletoe and hops are other well-known in- stances, which the reader should carefully ex- amine for himself at the proper season. All these are fivefold flowers, and I have brought them in here merely because one of the earliest and simplest threefold flowers we are going to consider has also this peculiarity of separate sexes. This is the common arrowhead, a plant that grows in watery ditches, and a capi- FIG. 20. I, male, and II, female flowers of arrowhead. tal example of the threefold type in its simpler development. Each flower, whether male or fe- male, has a green calyx of three small sepals, and a white corolla of three much larger and some- what papery petals (Fig. 20). But the male flowers have in their centre an indefinite number of clustering stamens ; while the female flowers have an equally numerous set of tiny carpels. The blossoms grow in whorls on the same stem, the males above, the females beneath them. At first sight you would think this a bad arrange- ment, because you might fancy pollen from the MORE MARRIAGE CUSTOMS. 109 males would certainly fall or blow out upon the females beneath them. But the plant prevents that catastrophe by a very simple dodge, which we shall have occasion to notice in many other parallel cases. The flowers open from below up- ward ; thus the females mature first, and are fer- tilised by insects which bring to them pollen from other plants already rifled ; later on the males follow suit, and their pollen is carried off by the visiting insect to the female flowers on the next plant it visits. Indeed, you may gather by this time how great a variety of devices natural selec- tion has produced for securing this great deside- ratum of fresh blood, or cross-fertilisation, from a totally distinct plant colony. A much commoner English wild-flower than the arrowhead shows us another form of early threefold blossom. I mean the water-plantain (Fig. 21), a pretty feath- ery weed, which grows by the side of most ponds and lakelets. In the wa- ter-plantain you have a flower of both sexes com- bined; it consists of three green sepals, forming a protective calyx ; three delicate pinky-white pet- als, forming the corolla; six stamens that is to say, two rows of three each ; and a number of small one-seeded carpels, exactly as in the buttercup, which occupies, in fact, the corresponding place among the fivefold flowers. FIG. 21. Flower of water- plantain. The male and fe- male parts are in the same blossom. IIO THE STORY OF THE PLANTS. But it is not often in the threefold flowers thai we get the calyx green and the corolla coloured, as in these simple and very early types. Most often in this great group of plants the calyx and corolla are both brightly coloured, and both alike employed as effective advertisements. A good case of this sort is shown in the flowering-rush, a close relation of the arrowhead and the water- plantain, but a more advanced and developed plant than either of them. Here the calyx and corolla, instead of forming two separate rows, are telescoped into one, as it were, and are both rose-coloured. In such cases we speak of the combined calyx and corolla as the perianth (another long word, with which I'm sorry to trouble you). In such perianths, however, even when all the pieces are of the same size and are similarly col- oured, you can see if you look close that three of them are outside and alternate with the others ; and these three are really the calyx in disguise, got up as a corolla. (An excellent example of this arrangement is afforded by the common garden tulip.) Inside its six rose-coloured perianth-pieces, the flowering-rush has nine stamens, arranged in three rows of three stamens each. Finally, in the centre, it has six carpels, equally arranged in two rows of three. Here the threefold architectural ground-plan of the flower is very apparent. You may say, in short, that the original scheme of the two great groups is something like this : five sepals, five petals, five stamens, five carpels ; or else, three sepals, three petals, three stamens, three carpels. But in any instance there may be two or more such rows of any organ, especially of the stamens ; in any instance certain parts may be reduced in number or entirely suppressed ; MORE MARRIAGE CUSTOMS. Ill and in any instance calyx and corolla may be coloured alike so as almost to resemble a single row or perianth. There is one more point about the flowering- rush to which I would like to allude before going on to the other threefold flowers, and that is this. In arrowhead and water-plantain the carpels are very numerous, but each one-seeded. In flower- ing-rush, on the other hand, which has a larger and handsomer blossom, more attractive to in- sects, they are reduced to six ; but these six have many seeds in each, so that a single act of fertili- sation suffices for each of them. You may re- member that among the fivefold flowers we found a precisely similar advance on the part of the marsh-marigold above the bulbous and meadow buttercups. This sort of advance is common in nature. Where a flower learns how to produce many seeds in a carpel, it can soon dispense with several of its carpels, because a few now do well what the many did badly. Furthermore, in higher plants, there is a tendency for these carpels to unite so as to form what we call a compound ovary, with a single style, when one act of fertilisation suffices for all of them. Such combinations or labour-saving arrangements obviously benefit both the insect and the plant, and have therefore been doubly favoured by natural selection. We see this advance beautifully illustrated in the largest and loveliest family of the threefold flowers, the lily group, which contains a great number of the handsomest msect-fertilised blos- soms, and is therefore deservedly an immense favourite in flower-gardens. All the lilies have a perianth (or combined calyx and corolla) of six almost similar brilliantly-coloured pieces (in which, 112 THE STORY OF THE PLANTS. however, you can still, as a rule, detect the sepals by their habit of overlapping the petals in the bud). Then they have a set of six stamens. Inside that again they have a single ovary, but if you cut it across with a penknife you will see at once it contains three chambers, each as a rule with several seeds ; and these three chambers are a memory of the time when the ovary consisted of three separate carpels. From their midst arises a single long style; but you may observe all the same that it is made up of three original and dis- tinct styles, because it divides at the top into three stigmas or sensitive surfaces. This is the general plan of the lily group ; but in certain individual lilies the stigma is undivided, and in others again the parts are increased to four or even to eight, so as to obscure the primitive threefold arrange- ment. Most of the large and handsome lilies culti- vated in gardens have perianths of separate pieces, such as one knows so well in the tiger-lily, the Turk's-cap lily, and the beautiful Japanese lilium auratum. They have also abundant honey, stored in a deep groove of the spotted petals, and they are variegated and lined in such a way as to guide insects direct to their store of nectar. But the family has been so successful with the higher insects, and has produced such an extraordinary variety of very beautiful and brilliant flowers, that it is quite impossible to speak of them in detail. A few among them, like our own wild hyacinth, show a slight tendency on the part of the petals and sepals to unite into a bell-shaped tube; still, even here the pieces are really distinct and separate. But in the true garden hyacinth the pieces unite into a tubular perianth, like the MORE MARRIAGE CUSTOMS. 113 tubular corolla of the common harebell, except that in the harebell the tube is formed by the union of the five petals, while in the hyacinth it is formed by the similar union of three petals and three sepals. A still higher form of the same union is shown us by the lily-of-the-valley, in which the six perianth-pieces join throughout to form a very beautiful heather-like cup or goblet. Other familiar members of this great lily group, which you ought to examine at leisure for your- self, in order to see how they are built up, are as- paragus, Solomon's seal, fritillary, tulip, star-of- Bethlehern, squill, garlic, onion, tuberose, and asphodel. The cultivated lilies of one sort or another to be found in our gardens may be num- bered by hundreds. A family of threefold flowers almost as beau- tiful as the lily group, and seldom distinguished from them save by botanists, is that which bears the pretty Greek name of amaryllids. The ama- ryllids are lilies which differ from the rest of their kind, in the fact that the perianth, still composed of six pieces, has grown up and around the ovary so as to seem to spring from above it, not below it. Such flowers are said to have " inferior ova- ries." In other respects the amaryllids closely resemble the lilies, having six coloured perianth- pieces, six stamens, and an ovary of three cham- bers, with one style in common. Several of the amaryllids are such familiar flowers that I shall venture to describe themes illustrative examples. The snowdrop is an amaryllid which blossoms in early spring, and which shows in a simple form the chief features of the family. It has six pe- rianth-pieces, but these are still distinctly recog- nisable as calyx and corolla. The three sepals 114 THE STORY OF THE PLANTS. are large and pure white, and they enclose the petals; the three petals are distinctly smaller, and tipped with green in a very pretty fashion. The summer snowflake, commonly cultivated in old- fashioned gardens, is very like the snowdrop, only here the difference between sepals and petals has disappeared; all six pieces form one apparent row, white, tipped with green, in a single perianth. In the daffodils and narcissuses we get a sec- ond group of amaryllids more advanced and de- veloped. Here the six perianth-pieces are almost alike, though they may still be distinguished as sepals and petals by a careful observer. But the perianth, which is tubular below, divides above into six lobes, beyond which it is prolonged again into what is called a crown, whose real nature can only be understood by comparison with such other flowers as the campions, where scales are inserted on the tip of the petals. This crown is compara- tively little developed in the narcissus and the jonquil ; but in the daffodil it has become by far the largest and most conspicuous part of the en- tire flower, so as completely to hide the bee who visits it. Of course this large crown assists fer- tilisation, and is a mark of advance in the daffodil and the petticoat narcissus. I hope these few remarks will induce you to examine many kinds of narcissus in detail, in order to see of what parts they are compounded. This seems a convenient place to interpose an- other remark I have long wanted to make, name- ly, that the threefold flowers are also for the most part distinguished by having those narrow grass- like or sword-shaped leaves, with parallel ribs or veins, about which I told you when we were deal- ing with the question of varieties of foliage. The MORE MARRIAGE CUSTOMS. 115 fivefold flowers, on the other hand, have usually net-veined leaves, either feather-ribbed or finger- ribbed. And at the risk of using two more horrid long words, I shall venture to add that botanists usually speak of the threefold group as monocoty- ledons, and of the fivefold group as dicotyledons. I did not invent these words, and I am sorry to have to use them here; but I will explain what they mean when I come to deal with seeds and seedlings. It is well at least to understand their use in case you come across them in your future reading. Another family of threefold flowers, closely allied to the amaryllids, is that of the irises^ many examples of which are familiar in our flower-gar- dens. It only differs from the amaryllids, in fact, > a having the number of stamens still further re- duced to three, which is always a sign of advance, because it shows that the plants are so sure of fertilisation as to be able to dispense with all unnecessary pollen. The ovary is also inferior, which you will learn in time to recognise as a constant sign of high development, because it means that the base of the corolla and calyx have coalesced with the carpels, and so ensured greater certainty of fertilisation. Some simple members of the iris group, like the crocuses, have mere tu- bular flowers, with a very long funnel-like base to the corolla, and with the ovary buried in the ground for greater safety. They are early spring blossoms, which need much protection against cold ; therefore they thus bury their ovaries, and sheathe their flower-buds in a papery covering, composed of a thin and leathery leaf. Whenever a sunny day comes in winter the bees venture out ; and on all such days, even though it freeze Il6 THE STORY OF THE PLANTS. in the shade, the crocuses are open in the sun- shine to welcome them. But other irises are more complicated, like the gladiolus, and still more the garden irises, in which the difference between the calyx and corolla is carried to its furthest point in this family. The sepals in true irises are large and brilliantly col- oured ; they hang over gracefully ; the petals are smaller and erect ; the stigmas are so expanded as to look like petals ; and they arch over the stamens in a most peculiar manner. If you watch a bee visiting a garden iris, you will see for your- self the use of this most peculiar arrangement; the bee lights on the bending sepal, and inserts his head between the stigma and the stamen in a way which renders fertilisation simply inevitable. But the most curious part of it all is that the flower, from the point of view of the bee, resem- bles three distinct and separate blossoms ; he alights one after another on each bending sepal, and proceeds to search for honey as if in a new flower. Highest of all the threefold flowers, and most wonderful in their marriage customs, are the great group of orchids, some of which grow wild in our English meadows, while others fix them- selves by short anchoring roots on the branches of trees in the tropical forests. Many of these last produce the handsomest and most extraor- dinary flowers in the world, and they are much cultivated accordingly in hothouses and con- servatories. It would be quite impossible for me to give you any account of the infinite devices invented by these plants to secure insect-fertilisa- tion ; and even the structure of the flower is so extremely complex that I can hardly undertake MORE MARRIAGE CUSTOMS. 117 to describe it to you intelligibly ; but I will give you such a brief statement of its chief peculiari- ties as will enable you to see how highly it has been specialised in adaptation to insect visits. The ovary in orchids is inferior, and curiously twisted. It supports six perianth-pieces, three of which are sepals, often long and very hand- some; while two are petals, often arching like a hood over the centre of the flower. The third petal, called the lip, is quite different in shape FIG. 22. Single flower of orchid, with the perianth cut away. The honey is in the spur, n ; the pollen-masses are marked a ; their gummy base is at r ; the stigma at st. and appearance from the other two, and usually hangs down in a very conspicuous manner. There are no visible stamens, to be recognised as such ; but the pollen is contained in a pair of tiny bags or sacks, close to the stigma. It is united into two sticky club-shaped lumps, usually called the pollen-masses (Fig. 22). In other words, the or- Il8 THE STORY OF THE PLANTS. chids have got rid of all their stamens except one, and even that one has united with the stigma. I will only describe the mode "of fertilisation of one of these plants, the common English spotted orchis ; but it will suffice to show you the extreme ingenuity with which members of the family often arrange their matrimonial alliances. The spotted orchis has a long tube or spur at the base of its sepals (Fig. 22, ?/), and this spur contains abun- dant honey. The pollen-masses are neatly lodged in two little sacks or pockets near the stigma, and are so placed that their lower ends come against the bee's head as he sucks the honey. These lower ends (r) are gummy or viscid, and if you press a straw or the point of a pencil against them, the pollen-masses gum themselves to it naturally, and come readily out of their sacks as you with- draw the pencil (Fig. 23). In the same way, when blG. 23. Pollen-masses of an orchid, withdrawn on a pencil. In I, they have just been removed. In II, they have dried and moved forward. the bee presses them with his head, the pollen- masses stick to it, and he carries them away with him as he leaves the flower. Just at first, the .pollen-masses stand erect on his forehead ; but as he flies through the air, they dry and contract, so that they come to incline forward and outward. MORE MARRIAGE CUSTOMS. By the time he reaches another plant they have assumed such a position that they are brought into contact with the stigma as he sucks the honey. But the stigma is gummy too, and makes the pollen adhere to it, and in this way cross- fertilisation is rendered almost a dead certainty. The result of these various clever dodges is that the orchids have become one of the dominant plant- families of the world, and in the tropics usurp many of the best and most favoured posi- tions (Fig. 24). Darwin has written a most romantic book on the numer- ous devices by which orchids alone attract insects to fertil- ise them. I will say no more of this family, therefore the highest and strangest among the threefold flowers save merely to advise those who wish to know more of this curious sub- ject to look it up in his charming volume. In- stead of pursuing the matter at issue further, I will give one final example in an opposite direc- tion. An opposite direction, I say, because all the threefold flowers we have hitherto been consider- ing are examples of a strict upward movement of evolution. Each group we have examined has been higher and more complex than the group before it. But I will now show you an instance, if not of degeneracy, at least of extreme simplifi- cation, which yet produces in the end the best possible results. This instance is that of the much enlarged. 120 THE STORY OF THE PLANTS. common English arum, known to children as cuckoo-pint or " lords and ladies " (Fig. 25). The structure of the cuckoo-pint is very pe- culiar. What looks like the flower is not really any part of the flower at all, but a large outer FiG. 25. The common arum, or cuckoo-pint, showing the spathe which surrounds the flowers, and the spike sticking up in the middle. leaf or spathe surrounding a group of very tiny blossoms. You can understand this leaf better if you look at a narcissus stalk, where a very similar leaf is seen to enclose a whole bunch of MORE MARRIAGE CUSTOMS. buds and opening flowers. Only, in the narcissus the spathe is thin, whitish, and papery, while in the cuckoo-pint it is expanded, green, and purple. Though not a corolla, it serves the same purpose as a corolla generally performs : it attracts insects to the compound flower-head. Inside the spathe we find a curious club-shaped mass, coloured bright purple, and standing straight up in the middle of the head. This is the stem or axis on which the separate little flowers are ar- ranged. Cut open the spathe, and you will find these flowers below in the centre (Fig. 26). At first sight what you see will look like a lot of confused little knobs ; but when you gaze closer you will see they separate themselves into three groups, which are the true flowers. Lowest of all on the stem come the female blos- soms, without calyx or corolla, each consisting of a single ovary. Above these in a group come the male flowers, equally devoid of calyx or corolla, and each con- sisting of a single stamen. Above these again come abortive or mis- shapen flowers, each of which has been reduced to a single down- ward-pointing hair. I will ex- plain first what is the use of these flowers in the cuckoo-pint as it stands to-day, and then I will go back to consider by what steps the plant came to develop them. The upper flowers, which look like hairs, and 122 THE STORY OF THE PLANTS. point all downwards, occupy a place in the com- pound flower-head just opposite the conspicuous narrowed part of the spathe which surrounds and encloses them. At this narrow point they form a sort of lobster-pot. It is easy enough for an in- sect to creep down past them, but very difficult or impossible for him to creep up in the opposite direction, as all the hairs point sharply downwards. Now, when the spathe unfolds, large numbers of a very small midge of a particular species are at- tracted into it by the purple club which rises like a barber's pole in the middle. If you cut a cuckoo-pint open during its flowering period you will always find a whole mob of these wee flies, crawling about in it vaguely, and covered from head to foot with pollen. They have come from another cuckoo-pint which they previously visited, and they have brought the pollen with them on their wings and bodies. But when they first reach the head, they find no pollen there ; the female flowers at the bottom ripen first, and the midges, creeping over the sensitive surface of these, fertilise them with pollen from the last plant they entered. Finding nothing to eat, if they could they would crawl out again ; but they can't, for the lobster-pot hairs prevent them. So they stop on perforce, having unwittingly fertilised the female flowers, but received themselves as yet no reward for their trouble. By and by, how- ever, after all the female flowers have been duly fertilised, the males above begin to ripen. When the stamens reach maturity, they shower down a whole flood of golden pollen on the expectant midges. Then the midges positively roll and revel in the flood, eating all they can, but at the same time covering themselves all over with a MORE MARRIAGE CUSTOMS. 123 dust of pollen-grains. As soon as the pollen is all shed, the downward-pointing hairs wither away ; the lobster-pot ceases to act ; and the midges are at liberty to fly away to another plant, where they similarly begin to fertilise the female flowers. Observe that, if the stamens were the first to ripen here, the pollen would fall on the stigmas of the same plant, but that, by making the stigmas be the first to mature, the cuckoo-pint secures for itself the desired end of cross-fertili- sation. In this case it is an interesting fact that all the stages which led to the existing arrangement of the flowers still remain visible in other plants for us. These very reduced little blossoms of the cuckoo-pint, consisting each of a single carpel or a single stamen, are yet the descendants of per- fect blossoms which had once a regular calyx and corolla. Near relations of the cuckoo-pint live in Europe and Africa to this day, which recapitulate for us, as it were, the various stages in its slow evo- lution. Some, the oldest in type, have a calyx and corolla, green and inconspicuous, with six stamens inside them, enclosing a two or three- celled ovary. These are still essentially lilies in structure. But they have the flowers clustered, as in cuckoo-pint, on a thick club-stem, and they have an open spathe, which more or less protects them. Our English sweet-sedge is still at this stage of evolution. The marsh-calla of Northern Europe and Canada, on the other hand, has a handsome white spathe to attract insects, while its separate flowers, still both male and female to- gether, have each six stamens and a single ovary. But they have lost their perianth. The common white arum or " calla lily " of cottage gardens has 124 THE STORY OF THE PLANTS. a bright yellow spike in its midst, and if you look at it closely you will see that this spike consists entirely of a great cluster of stamens, thickly massed together. The top of the spike is en- tirely composed of such golden stamens, but lower down you w r ill find ovaries embedded here and there among them, each ovary as a rule sur- rounded by five or six stamens. Lastly, in the cuckoo-pint the lower flowers have lost their com- plement of stamens altogether, while the upper ones have similarly lost their ovaries ; moreover, a few of the topmost have been converted into the curious lobster-pot hairs which assist, as I have shown you, in the work of fertilisation. We have here a singular and instructive exam- ple of what may be described as retrograde develop- ment. And now we must go on to those modes of fertilisation which are effected by agencies other than insects. CHAPTER IX. THE WIND AS CARRIER. ALL flowers do not depend for fertilisation upon insects. In many plants it is the wind that serves the purpose of common carrier of pollen from blossom to blossom. Clearly, flowers which lay themselves out to be fertilised by the wind will not be likely to pro- duce the same devices as those which lay them- selves out to be fertilised by insects. Natural selection here will favour different qualities. Bright-coloured petals and stores of honey will THE WIND AS CARRIER. 125 not serve to allure the unconscious breeze; such delicate adjustments of part to part as we saw in ihe case of bee and blossom will no longer be serviceable. What will most be needed now is quantities of pollen ; and that pollen must hang out in such a way from the cup as to be easily dislodged by passing breezes. Hence wind-fertil- ised flowers differ from insect-fertilised in the following particulars. They have never brilliant corollas or calyxes. The stamens are usually very numerous; they hang out freely on long stalks or filaments ; and they quiver in the wind with the slightest movement. On the other hand, the stigmas are feathery and protrude far from the flower, so as to catch every passing grain of pollen. More frequently than among the insect- fertilised section, the sexes are separated on dif- ferent plants or isolated in distinct masses on neighbouring branches. But numerous devices occur to prevent self-fertilisation. You must not suppose, again, that the wind- fertilised plants form a group by themselves, dis- tinct in origin from the insect-fertilised, as the three-petalled group is distinct from the five- petalled. On the contrary, wind-fertilised kinds are found abundantly in both great groups; it is a matter of habit; so much so that sometimes a type has taken first to insect-fertilisation and then to wind-fertilisation, with comparatively slight differences in its external appearance. Closely related plants often differ immensely in their mar- riage customs ; each has varied in the way that best suited itself, according as insects or breezes happened to serve it most readily. In my own opinion all wind-fertilised plants are the descend- ants of insect-fertilised ancestors; but I do not 126 THE STORY OF THE PLANTS. know whether in this belief my ideas would be accepted by most modern botanists. As a first example of wind-fertilised flowers, I will take the common dog's mercury, a well- known English wayside flower, frequent in copses and hedgerows, and one of the very earliest to blossom in spring. In this species the males and females grow on separate plants. They have each a calyx of three sepals (two more being sup- pressed, for they belong by origin to the fivefold division). The males have ten or twelve stamens apiece, which hang out freely with long stalks to the breeze. The females have a two-chambered ovary, with rudiments or relics of some two or three stamens by its side, showing that they are descended from earlier combined male-and-female ancestors. The relics, however, consist of mere empty stalks or filaments, without any pollen- sacks. Of course there are no petals. Male and female plants grow in little groups not far from one another ; and the pollen, which is dry and dusty, is carried by the wind from the hanging stamens of the males to the large and salient stigma of the female flowers. A still better example of a wind-fertilised blossom is afforded us by the common English salad-burnet, a pretty little weed, very frequent on close-cropped chalk downs (Fig. 27). Here the individual flowers are extremely small, and they are crowded into a sort of mop-like head at the top of the stem. They have lost their petals, which are now of no use to them ; but they retain a calyx of four sepals, to represent the original five still found among their relations. For salad- burnet, in spite of its inconspicuousness, belongs to the family of the roses, and we can still trace in THE WIND AS CARRIER. 127 this order a regular gradation from handsome flowers like the dog-rose, through smaller and smaller blossoms like the strawberry and the potentilla, to green petalless types like lady's- mantle and parsley-piert, or, last of all, to wind- fertilised blossoms like those of the salad-burnet. In the male flowers the very numerous stamens hang out on long thread-like stalks from the wee green cup, so that the wind may readily catch and carry the pollen ; in the female blossoms the stigma is divided into plume- like brushes, which readily entrap any passing pollen-grain. Moreover, though both kinds of flower grow on the same A head, the females are FIG. 27. A, male, and B, female rnnctUT- at th^ tnn nf flower of salad-burnet, very much mostly at tne top Ot magnified. The flowers grow to- the bunch and the gether in little tassel-like heads. males below them. This makes it difficult for the pollen from the same head to fertilise the females, as it would easily do if the males were at the top. Nor is that all ; the female flowers open first on each head, and hang out their pretty feathery stigmas to the breeze that bends the stem ; as soon as they have been fertilised from a neighbour plant, the males in turn begin to open, and shed their pollen for the use of other flowers. In salad-burnet, however, the division of the sexes into separate flowers has not become a quite fixed habit ; for, though most of the blossoms are either male or female only, 128 THE STORY OF THE PLANTS. as shown in the figure, we often find a cup here and there which contains both stamens and pistil together. I have already told you that in many plants the calyx helps the corolla as an advertisement for insects; and sometimes, as in the marsh- marigold and the various anemones, where there are no petals at all, it becomes so brilliant as to be mistaken for petals by all but botanists. One way in which such a substitution often happens is shown us by the great burnet, which is a close relation of the salad-burnet. This plant, after having acquired the habit of wind-fertilisation, has taken again at last to insect marriage. Hav- ing lost its petals, however, it can't easily rede- velop them; so it has had instead to make its calyx purple. The plant as a whole closely re- sembles the salad-burnet; but the flowers are rather different ; the stamens no longer hang out of the calyx ; the calyx cup is more tubular; and the stigma is shortened to a little sticky knob, instead of being divided into feathery fringes. These differences are all very characteristic of the contrast between wind and insect-fertilisation. The common nettle supplies us with an excel- lent example of another form of wind-fertilisa- tion, carried to a still higher pitch of develop- ment. Here the sexes grow on different plants, and the flowers are tiny, green, and inconspicu- ous. The males consist of a calyx of four sepals, each sepal with a stamen curiously caught under it during the immature stage. But as soon as they ripen they burst out elastically, and shoot their pollen into the air around them. In this case, and in many like it, the plant itself helps the wind, as it were, to disseminate its pollen. THE WIND AS CARRIER. I2 9 The common English bur- reed is a waterside plant of great beauty which shows us another interesting instance of wind-fertilisation in an ad- vanced condition (Fig. 28). Here the separate flowers are very much reduced as sim- ple, in fact, as those of the cuckoo-pint. The males con- sist of nothing but stamens, gathered in close globular heads, with a few small scales interspersed among them, which seem to represent the last relics of a calyx. The females are made up of single ovaries, each surrounded by three or six scales, still form- ing a simple rudimentary ca- lyx. They, too, are clustered in round heads or masses on antler -like branches. The plant belongs to the threefold group, and represents a very degenerate descendant of a primitive ancestor something like the arrowhead already described in the last chapter. But the arrangement of the heads on the stem is very in- teresting. The balls at the top are entirely composed of male flowers; those at the bottom are exclusively female. FIG. 28. Flowers of bur- reed. The two lower heads consist of female blossoms, the five upper ones of males. Only one head of the males is mature ; the others are still in the bud. The female flow- ers ripen first, and receive pollen by aid of the Q 130 THE STORY OF THE PLANTS. wind from some other plant that grows close by them. As soon as they have begun to set their seeds the stigmas wither, and then the male flow- ers open in a bright yellow mass, the stalks of their stamens lengthening out as they do so, and allowing the wind to carry the pollen freely. Here, although the males are above, the peculiar arrangement by which the females ripen first makes it practically impossible for the flowers to be fertilised by pollen from their immediate neigh- bours. The devices for wind-fertilisation, however, are on the whole less interesting than those for insect-fertilisation, so I shall devote little more space to describing them. I will only add that two great classes of plants are habitually wind- fertilised : one includes the majority of forest trees ; the other includes the grasses, sedges, and many other common meadow plants. The wind-fertilised forest trees belong for the most part to the fivefold group, and have their flowers, as a rule, clustered together into hang- ing and pendulous bunches, which we call catkins. It is obvious why trees should have adopted this mode of fertilisation, because they grow high, and it is easy for the wind to move freely through them. For this reason, most catkin-bearing trees flower in early spring, when winds are high, and when the trees are leafless ; because then the foliage doesn't interfere with the proper carriage of the pollen. In summer the leaves would get in the way ; the pollen would fall on them ; and the stigmas would be hidden. Most catkins are long, and easily moved by the wind ; they have numer- ous flowers in each, and they shake out enormous quantities of pollen. This you can see for your- THE WIND AS CARRIER. i^i self by shaking a hazel branch in the flowering season, when you will find yourself covered by a perfect shower of pollen. In hazel (Fig. 29) the male and female flowers grow on the same tree, but are most different to look at. You would hardly take them for cor- responding parts of the same species. The male flowers are grouped in long sausage-shaped cat- kins, each blossom covered with a tiny brown scale, and all arranged like tiles on a roof against the cold of winter. There are about eight sta- mens to each blossom, with little trace of a calyx FIG. 29 Flowers of the hazel. I, a single male flower, removed from a catkin ; II, a pair of female flowers ; III, a female catkin. or corolla. But the females are grouped in funny little buds, like crimson tufts, well protected by scales; they consist of the future hazel-nut, with a red style and feathery stigma projecting above to catch the pollen. Here the flowers are very little like the regular types with which we are familiar; yet intermediate cases help to bridge over the gap for us. For example, in the alder we get a type which seems to stand half-way between the nettle and the hazel (so far, I mean, as the arrangement of the flower is concerned, for otherwise the nettle 132 THE STORY OF THE PLANTS. belongs to a quite different family). The male and female catkins of the alder grow on the same tree; the males consist of numerous clustered flowers, three together under a scale, which never- theless, when we take the trouble to pick them out and examine them with a pocket-lens, are seen to resemble very closely the male flowers of the nettle. Each consists of a four-lobed calyx, with four stamens opposite the sepals. The fe- male flowers have degenerated still further, and consist of little more than a scale and an ovary. Other well-known wind-fertilised, catkin-bear- ing trees are the oak, the beech, the birch, and the hornbeam. But the willows, though they bear catkins, and were once no doubt wind-fertilised, have now returned once more to insect-fertilisa- tion, as you can easily convince yourself if you stand under a willow tree in early spring, when you will hear all the branches alive with the buzz- ing of bees, both wild and domestic. Neverthe- less, the willow, having once lost its petals, has been unable to develop them again. Still, its catkins are far handsomer and more conspicuous than those of its wind-fertilised cousins, owing to the pretty white scales of the female bunches, and the numerous bright yellow stamens of the males. It is this that causes them to be used for " palm " in churches on Palm Sunday. The male and fe- male catkins grow on different trees, so as to en- sure cross-fertilisation, and the difference between the two forms is greater perhaps than in almost any other plant, the males consisting of two showy stamens behind a winged scale, and the females of a peculiar woolly-looking ovary. Even more important is the great wind-fertil- ised group of the grasses, to which belong by far THE WIND AS CARRIER. 133 the most useful food-plants of man, such as wheat, rice, barley, Indian corn, and millet. Grasses are for the most part plants of the open wind-swept plains, and they seem naturally to take therefore to wind-fertilisation. Their flowers are generally small, clustered into light spikes or waving panicles, and hung out freely to the breeze on slender and very movable stems, so as to yield their pollen to every breath of air that passes. Moreover, the plants as a whole are slender and waving, so that they bend before the breeze in the mass, as one often sees in a meadow or cornfield. Thus the grasses are almost the pure type of wind-fertilised plants; certainly they have carried further than any other race the devices which render wind-fertilisation more certain. On this account they are so complicated and varied that I will not attempt to describe them in detail. I will only say that grasses are descend- ants of the threefold flowers, and in all proba- bility degenerate lilies. Their individual blos- soms usually consist of a very degraded calyx (d and e] of two sepals (one of which represents a pair that have coalesced, Fig. 30). Inside these sepals come two very minute white petals (c and c] ; the third has disappeared, owing to pressure one-sidedly. The petals can scarcely be seen without the aid of a pocket-lens. Next comes three stamens (b\ the only part of the flower which still preserves the original threefold ar- rangement. Last of all we get the ovary (#), of one carpel, one seeded, but with two feathery stigmas, which were once three. In a very few large grasses, such as the bamboos, the threefold arrangement is much more conspicuous. As a 134 THE STORY OF THE PLANT". rule the stamens of grasses hang out freely to the wind, and the stigmas are feathery and most graceful in outline (Fig. 31). The flowers are usually collected in spikes like that of wheat, or in loose clusters like oats; they frequently hang over in pendulous bunches. Their success may FlG. 30. A flower of wheat, FlG. 31. Flower of wheat, with with its parts divided, a, the calyx of two chaffy scales the carpel and stigmas ; , removed This shows the the stamens ; c, the petals, arrangement of petals, sta- very minute ; d and e, the mens, and ovary, calyx. be gathered from the fact that almost all the great plains, in the world, such as the American prairies, the Pampas, and the Steppes, are covered with grasses; while even in hilly countries the valleys and downs are also largely clad with smaller and more delicate species. No plants assume so great a variety of divergent forms; the total number of kinds of grasses can hardly be estimated ; in Britain alone we have more than a hundred native species. HOW FLOWERS CLJB TOGETHER. 135 I will give no further examples of wind- fertilised flowers. If you look for yourself you can find dozens on all sides in the fields around you. They may almost always be recognised by these two marked features of the hanging stamens and the feathery stigma. Before I pass on to another subject, however, I ought to mention that by no means all flowers are regularly cross-fertilised. There are some degraded types in which self-fertilisation has be- come habitual. In these plants, which are usually poor and feeble weeds like groundsel and shep- herd's purse, the stamens bend round so as to impregnate the pistil in the same blossom. In other less degraded cases the flower is occasion- ally cross-fertilised by insect visits; but if no insect turns up in time, the stamens, even in handsome and attractive blossoms, often bend round and impregnate the pistil. A very good example of this is seen in our smaller English mallow, which has large mauve flowers to attract insects; but should none come to visit it, the stamens and stigmas at last intertwine, and self- fertilisation takes place, for want of better. Still, as a general rule, it holds good that self-fertilisa- tion belongs to scrubby and degraded plants; it is only adopted as a last resort when all other means fail by the superior species. CHAPTER X. HOW FLOWERS CLUB TOGETHER. IN the preceding chapters I have dealt for the most part with individual flowers ; I have spoken 136 THE STORY OF THE PLANTS. of them separately, and of the work they do in getting the seeds set. Incidentally, however, it has been necessary at times to touch slightly upon the way they often mass themselves into heads or clusters for various purposes ; and we must now begin to consider more seriously the origin and nature of these co-operative societies. Very large flowers, like the water-lily, the tulip, the magnolia, the daffodil, are usually soli- tary ; they suffice by themselves to attract in sufficient numbers the fertilising insects. But smaller flowers often find it pays them better to group themselves into big spikes or masses, as one sees, for example, in the foxglove and the lilac. Such an arrangement makes the mass more conspicuous, and it also induces the insect, when he comes, to fertilise at a single visit a large num- ber of distinct blossoms. It is a mutual conven- ience ; for the bee or butterfly, it saves valuable time ; for the plant, it ensures more prompt and certain fertilisation. In many families, therefore, we can trace a regular gradation between large and almost solitary flowers, through smaller and somewhat clustered flowers, to very small and comparatively crowded flowers. Thus the largest lilies are usually solitary or grow at best three or four together, like the lilium auratum / in the tuberose and asphodel, where the individual blos- soms are smaller, they are gathered together in big upright spikes; in the hyacinth, the clustering is closer still ; while in wild garlic, grape-hya- cinth, and star-of-Bethlehem, the arrangement assumes the form of a flat-topped bunch or a globular cluster. Of course, small flowers are sometimes solitary, and large ones sometimes clustered; but as a general rule the tendency is HOW FLOWERS CLUB TOGETHER. 137 for the big blossoms to trust to their 6wn indi- vidual attractions, and for the little bn'es to feel that union is strength, and to organise" accord- ingly. Botanists have invented many technical names for various groupings of flowers in particular fashions, with most of which I will not trouble you. It will be sufficient to recall mentally the very different way in which the flowers are ar- ranged in the lily-of-the-valley, the foxglove, the Solomon's seal, the heath, the scabious, the cow- slip, the sweet-william, the forget-me-not, in order to see what variety natural selection has produced in all these matters. Two instances must serve to illustrate their mode of action. The foxglove grows in hedgerows and thickets, and turns its one-sided spike towards the sun and the open ; its flowers open regularly from below upward, and are fertilised by bees, who enter the blossoms, and whose body is beautifully adapted to come in contact, first w T ith the stamens, and later with the stigma. (Examine this familiar flower for your- self in the proper season.) In the forget-me-not, on the other hand, the unopened flowers are coiled up like a scorpion's tail ; but as each one opens, the stem below it lengthens and unrolls, so that at each moment the two or three flowers just ready for fertilisation are displayed conspicuously at the top of the apparent cluster. There are two forms of cluster, however, so specially important that I cannot pass them over here without some words of explanation. These are the umbel and the head, both of frequent oc- currence. An umbel is a cluster in which the flowers, standing on separate stalks, reach at last the same level, so as to form a flat-topped mass, 138 THE STORY OF THE PLANTS. like the surface of a table. An immense family of plants has very small flowers arranged in such an order ; they are known as umbellates, and FIG. 32. Clusters of flowers. I, spike of mercury, green, wind- fertilised ; II, panicle of a grass (brome), green, wind-fertilised ; III, head of Dutch clover, the upper flowers unvisited as yet by insects ; the lower fertilised, and turning down to make room for their neighbours. they include hemlock, fool's parsley, cow-parsnip, carrot, chervil, celery, angelica, and samphire. In other families the same form of cluster is seen HOW FLOWERS CLUB TOGETHER. 139 in ivy and garlic. A head, again, is a cluster in which the individual flowers are set close on very short stalks or none at all in a round ball or a circle. Clover and scabious are excellent ex- amples of this sort of co-operation. If you examine a head of common white Dutch clover (Fig. 32, iii.), you will see for yourself that it is not, as you might suppose, a single flower, but a thick mass of small white pea-like blos- soms, each on a stalk of its own, and each pro- vided with calyx, corolla, stamens, and pistil. They are fertilised by bees ; and as soon as the bee has impregnated each blossom, it turns down and closes over, so as to warn the future visitor that he has nothing to expect there. The flowers open from below and without, upward and in- ward ; and there is always a broad line between the rifled and fertilised flowers, which hang down as if retired from business, and the fresh and up- standing virgin blossoms, which court the bees with their bright corollas. Sometimes you will find a head of clover in which all the flowers save one have already been fertilised ; and this one, a solitary old maid as it were, stands up in the cen- tre still waiting for the bees to come and ferti- lise it. By far the most interesting form of head, how- ever, is that which occurs in the daisy, the sun- flower, the dandelion, and their allies, where the club or co-operative society of united blossoms so closely simulates a single flower as to be univer- sally mistaken for one by all but botanical ob- servers. To the world at large a daisy or a dahlia is simply a flower ; in reality it is nothing of the sort, but a city or community of distinct flowers, differing widely from one another in structure 140 THE STORY OF THE PLANTS. and function, but all banded together in due sub- ordination for the purpose of effecting a common object. There is avast and very varied family of such united flowers, known as the composites; it stands at the head of the fivefold group of flower- ing plants, as the orchids stand at the head of the threefold ; and it is so widely spread, it includes so large a proportion of the best-known plants, and it fills so great a space in the vegetable world generally, that I cannot possibly pass it over even FIG. 33. Single floret from the FIG. 34. Single floret from the centre of a daisy. centre of a daisy, with the co- rolla opened, much enlarged in so brief and hasty a history as this of the de- velopment of plants on the surface of our planet. If you pick a daisy you will think at first sight it is a single flower. But if you look closer into it you will see it is really a great group of flowers a compound flower-head, composed of many dozen distinct blossoms or florets, as we call them (Fig. 33). These, however, are not all alike. The florets in the centre, which you took no doubt at first sight for the stamens and pistils, are small yellow tubular blossoms, each with a HOW FLOWERS CLUB TOGETHER. 141 combined corolla of five lobes, little or no visible calyx, five stamens united in a ring round the style, and a pistil consisting of an inferior ovary, with a style divided above into a twofold stigma (Fig. 34). Here we have clear evidence that the plant belongs by origin to the five-petalled group ; it rather resembles the harebell, in the plan of its flower, on a much smaller scale; but it has almost lost all trace of a separate calyx, it has its five petals united into a tubular corolla, it has still its original five stamens, but its carpels are now re- duced to one, with a single seed, though traces of an earlier intermediate stage, when the carpels were two, remains even yet in the di- vided stigma. So much for the inner flowers or florets in the daisy. The outer ones, which you took at first no doubt for petals, are very different in- deed from these central blos- soms. They have an ex- tremely curious long, strap- shaped corolla (Fig. 35), open down the side, but tubular at its base, as if it had been split through the greater part of its length by a sharp pen- knife. Instead of being yel- low, too, these outer florets are white, slightly tinged with pink, and they form the largest and most attractive part of the whole flower-head. Furthermore, they are female only ; they have a style and ovary, but no stamens. Clearly, we have FIG. 35. Single floret from the ray of a daisy, pink and white, with an ovary, but no stamens. 142 THE STORY OF THE PLANTS. here a flower-head with numerous unlike flowers, which at once suggests the idea of a division of labour between the component members. How this division works we shall see in the sequel. The best way to see it is to follow up in detail the evolution of the daisy and the other com- posites from an earlier ancestor. We saw already how the petals combined in the harebell and many other flowers so as to form a tubular corolla. A purple flower of some such type seems to have been the starting-point for the development of the great composite family. The individual blos- soms in the common ancestral form seem to have been small and numerous ; and, as often happens with small flowers, they found that by grouping themselves together in a flat head they succeeded much better in attracting the attention of the fer- tilising insects. Many other tubular flowers that are not composites have independently hit upon the same device; such are the scabious, the devil's-bit, the sheep's-bit, and the rampion. But these flowers differ from the true composites in two or three particulars. In the first place, each tiny flower has a distinct green calyx, of five se- pals ; while the composites have none, or at least a degraded one. In the second place, the stamens are free, while in the composites they have united in a ring or cylinder. In the third place, the ovary is divided into from two to five cells, a rem- iniscence of the original five distinct carpels; whereas in the composites the ovary is always single and one-seeded. In all these respects, therefore, the composites are later and more ad- vanced types than, say, the sheep's-bit, which is a flower-head composed of very tiny harebells. The composites, then, started with florets which HOW FLOWERS CLUB TOGETHER. 143 had little or no calyx, the sepals having been con- verted into tiny feathery hairs, used to float the fruit (as in thistledown and dandelion), about which we shall have more to say in a future chap- ter. They had a corolla of five purple petals, com- bined into a single tube. Inside this again came five united stamens, and in the midst of all an in- ferior ovary with a divided stigma. Hundreds of different kinds of composites now existing on the earth retain to this day, in the midst of the great- est external diversity, these essential features, or the greater part of them. You may take thistle as a good example of the composite flowers in an early and relatively simple stage of development (Fig. 36). Here the whole flower-head resembles a single large purple blos- som. To increase the resemblance, it has below it what seems at first sight to be a big green calyx of very numerous sepals. What is this deceptive object ? Well, it is called an involucre, and it really acts to the compound flower-head very much as the calyx acts to the single blossom. The florets having got rid of their separate calyxes, the flower- head provides itself with a cup of leaves (tech- nically called bracts), which protect the unopened head in its early stages, and serve to keep off ants or other creeping insects exactly as a calyx does for the single flower. Inside this involucre, again, all the florets of the thistle are equal and similar. Each has a tiny calyx, hardly recognisable as such, made up of feathery hairs which cap the inferior ovary. Within this fallacious calyx, once more, the floret has a purple corolla of five petals, united into a tube. Then come the five united stamens, and the pistil with its divided stigma. This is the simplest and central form of compos- 144 THE STORY OF THE PLANTS. ite, from which the others are descended with various modifications. To this central type belong a large number of well-known plants, both useful and ornamental, though more particularly deleterious. Among them may be mentioned the various thistles, such as the common thistle, the milk thistle, the Scotch thistle, and so forth, most of which have their involucres, and often their leaves as well, extremely prickly, so as to ward off the attacks of goats and cattle. The bur- dock, the artichoke, the saw - wort, and the globe-thistle also be- long to the same cen- tral division. Among these earlier compos- ites, however, there is one group, that of the centauries, which leads us gradually on to the next division. Our com- FIG. 3 6.-Flowcr-head of a thistle, mones t centaury in consisting of very numerous _ . . .. * purple florets, all equal and Britain (known to boys similar. as hardheads) has all the florets equal and similar, and looks in the flower very much like a thistle. But one of its forms, and most of the cultivated garden centauries, have the outer florets much larger and more broadly open than the cen- HOW FLOWERS CLUB TOGETHER. 145 tral ones, so that they form an external petal-like row, which adds greatly to the attractiveness of the entire flower-head. Of this type, the common blue cornflower is a familiar example. Clearly the plant has here developed the outer florets more than the inner ones in order to make them act as extra special attractions to the insect fertilisers. The more familiar type of composites so much cultivated in gardens carries these tactics a step further. We saw reason to believe in a previous chapter that petals were originally stamens, flat- tened and brightly coloured, and told off for the special attractive function. Just in the same way the ray-florets of the daisy, the sunflower, the single dahlia, and the aster are florets which have been flattened and partially or wholly sterilised in order to act as allurements to insects. The ray-floret acts for the compound flower-head as the petal acts for the individual blossom. In many other families of plants besides the composites we get foreshadowings, so to speak, of this mode of procedure. The outer flowers of a cluster, be it head or umbel, are often rendered larger so as to increase the effective attractive- ness of the whole ; and sometimes they are sacri- ficed to the inner ones by being made neuter or sterile, that is to say, being deprived of stamens and pistil. Thus in cow-parsnip, which is a mem- ber of the same family as the carrot and the hem- lock, the outer flowers of each umbel are much larger than the central ones, while in the. wild guelder-rose the central flowers alone are fertile, the outer ones being converted into mere ex- panded white corollas with no essential floral organs. But it is the composites that have car- ried this process of division of labour furthest, 10 146 THE STORY OF THE PLANTS. by making the ray-florets into mere petal-like straps, which do no work themselves, but simply serve to attract the fertilising insects to the com- pound flower-head. An immense number of these composites with flattened ray-florets grow in our fields or are cul- tivated in our gardens. In the simpler among them, such as the sunflower, the corn-marigold, the ragwort, and the golden-rod, both ray-florets and central florets are simply yellow. But in others, such as the daisy, the ox-eye daisy, the aster, and the camomile, the ray-florets differ in colour from those of the centre ; the latter re- main yellow, while the former become white, or are tinged with pink, or even flaunt forth in scar- let, crimson, blue, or purple. Of this class one may mention as familiar instances the dahlia, the zinnia, the Michaelmas daisies, the cinerarias, and the pretty coreopsis so common in our gardens. Gardeners, however, are not content to let us ad- mire these flowers as nature made them. They generally "double "them that is to say, by care- fully selecting certain natural varieties, they pro- duce a form in which all the florets have at last become neutral and strap-shaped. This is well seen in the garden chrysanthemum, where, how- ever, if you open the very centre of the doubled flower-head, you will generally find in its midst a few remaining fertile tubular blossoms. The same process is also well seen in the various stages between the single and the double dahlia. Such "double" composites can set little or no seed, and are therefore from the point of view of the plant mere abortions. Nor are they beauti- ful to an eye accustomed to the ground plan of floral architecture. Remember, of course, that HOW FLOWERS CLUB TOGETHER. 147 what we call " a double flower " in a rose, a but- tercup, or any other simple blossom is one in which the stamens have been converted into super- numerary and useless petals; while in a composite it is a flower-head in which the central florets have been converted into barren ray-florets. In either case, however, the result is the same the flowers are rendered abortive and sterile. Nature's way is quite different. Here is how she manages the fertilisation of one of these ray- bearing composites say for example the sun- flower, where the individual florets are quite big enough to enable one to follow the process with the naked eye. The large yellow rays act as ad- vertisements ; the bee, attracted by them, settles on the outer edge and fertilises the flowers from without inward. To meet this habit of his, the florets of the sunflower pass through four regu- lar stages. They open from without inward. In the centre are unopened buds. Next come open flowers, in which the stamens are shedding their pollen, while the stigmas are still hidden within the tube. Third in order, we get florets in which the stamens have withered, while the stigmas have now ripened and opened. Last of all, we get, next to the rays, a set of overblown florets, en- gaged in maturing their fertilised fruits. The bee thus comes first to the florets in the female stage, which he fertilises with pollen from the last plant he visited ; he then goes on to florets in the male stage, where he collects more pollen for the next plant to which he chooses to devote his attention. The florets of the sunflower are interesting also for the fact that, unlike most composites, they still retain obvious traces of a true calyx. 148 THE STORY OF THE PLANTS. The composites which produce purple or blue ray-florets to attract insects are in some ways the highest of their class. Still, there is another group of composites which has proceeded a little further in one direction ; and that is the group which in- cludes the dandelions. In these heads all the florets alike have become strap-shaped or ray- like; but they differ from the double composites of the gardeners in this, that each floret still re- tains its stamens and pistil. The composites of the dandelion group are chiefly weeds like the hawkbit and the sow-thistle. A few are cultivated as vegetables, such as lettuce, salsify, chicory, and endive ; fewer still are prized for their flow- ers for ornamental purposes, such as the orange hawkweed. The prevailing colour in this class is yellow, and the devices for insect-fertilisation are not nearly so high as in the ray-bearing group. I regard them as to a great extent a retrograde tribe of the composite family. In this chapter I have dealt chiefly with the co-operative clubbing together of insect-fertilised flowers, for purposes of mutual convenience; but you must not forget that similar clubs exist also among the wind-fertilised blossoms in quite equal profusion. Such are the catkins of forest trees, the panicles of grasses, the spikes of sedges, and the heads of the black-cap rush and many other water-plants. Some of these, such as the bur- reed, we have already considered. Lastly, I ought to add that where the flowers themselves are inconspicuous, attention is often called to them by a bright-coloured leaf or group of leaves in their immediate neighbourhood. We saw an instance of this in the great white spathe or folding leaf which encloses the male and female WHAT PLANTS DO FOR THEIR YOUNG. 149 flowers of the " calla lily." In the greenhouse poinsettia the individual flowers are tiny and un- noticeable; but they are rich in honey, and round them has been developed a great bunch of bril- liant scarlet leaves which renders them among the most decorative objects in nature. A laven- der that grows in Southern Europe has dusky brown flowers; but the bunch is crowned by a number of mauve or lilac leaves, hung out like flags to attract the insects. A scarlet salvia much grown in windows similarly supplements its rather handsome flowers by much handsomer calyxes and bracts which make it a perfect blaze of splen- did colour. It doesn't matter to the plant how it produces its effect; all it cares for is that by hook or by crook it should attract its insects and get itself fertilised. CHAPTER XL WHAT PLANTS DO FOR THEIR YOUNG. AFTER the flower is fertilised it has to set its seed. And after the seed is set the plant has to sow and disperse it. Now, the fruit and seed form the most difficult part of technical botany, and I will not apologise for treating them here a little cavalierly. I will tell you no more about them than it is actually necessary you should know, leaving you to pur- sue the subject if you will in more formal treatises. The pistil, after it has been fertilised and ar- rived at maturity, is called the fruit. In flowers like the buttercup, where there are many carpels, the fruit consists of distinct parts, each one-seeded 150 THE STORY OF THE PLANTS. little nuts in the meadow buttercup, but many- seeded pods in the marsh-marigold and the lark- spur. Where the carpels have combined into a single ovary, we get a many-chambered fruit, as in the poppy, which consists, when cut across, of ten seed-bearing chambers. Most fruits are dry capsules or pods, either single, as in the pea, the bean, the vetch, and the laburnum ; or double, as in the wallflower and shepherd's-purse ; or many- chambered, as in the lily, the wild hyacinth, the poppy, the campion. As a rule the fruit consists of as many carpels or as many chambers as the unfertilised ovary. Fruits are often dispersed entire, and this is especially true when they contain only one or two seeds. In such instances they sometimes fall on the ground direct, as is the case with most nuts ; or else they have wings or parachutes which enable the wind to seize them, and carry them to a distance, where they can alight on unex- hausted soil, far away from the roots of the mother plant. Such fruits are common among forest trees. The maples, for example, have a double fruit, often called a key, which the wind whirls .away as soon as the seeds are ready for dispersion (Figs. 37, 38, 39, 40, 41). In the lime, the common stalk of the flowers is winged by a thin leaf; and when the little nuts are ripe the wind detaches them and carries them away by means of this joint parachute. In the birch, elm, and ash the fruit is a one-seeded nut, with its edge produced into a leathery or papery wing, w r hich serves to float it. But more often the fruit at maturity opens and scatters its seeds, as we see in the pea, the wild hyacinth, and the iris. Sometimes the seeds WHAT PLANTS DO FOR THEIR YOUNG. 151 so released merely drop upon the ground, but most often some device exists for scattering them to a distance, so as to obtain the advantage of unexhausted soil for the young seedling. Thus most capsules open at the top, so that the seeds can only drop out when the wind is high enough to carry them to some distance. In the poppy- 152 THE STORY OF THE PLANTS. head the capsule opens by pores at the side, and, if you shake one as it grows, you will find it takes a considerable shaking to dislodge the seeds from the walls of their chamber. Thus only in high winds are the poppy seeds dispersed. In the mouse-ear chickweed the capsule is directed slightly upward at the end for a similar purpose. Sometimes, again, the valves of the fruit open elastically and shoot out the seeds; this device is familiarly known in the garden balsam, and it occurs also in the little English wallcress. The sandbox-tree of the West Indies has a large round woody capsule, which bursts with a report like a pistol, and scatters its seeds with such violence as to inflict a severe wound upon anybody who hap- pens to be struck by them. Where seeds are numerous, they are oftenest dispersed in some such manner, by the capsule opening naturally and scattering its contents; but where they are few in number, it more fre- quently happens that the fruit does not open, as in the oak or the elm; and when there is only one seed, the fruit and seed become almost indistin- guishable, and are popularly regarded as a seed only. For example, in the pea, we distinguish at once between the pod, which is a fruit containing many seeds, and the pea which is one such seed among the many ; but in wheat or oats the fruit is small and one-seeded, and its covering is so closely united with the seed as to be practically inseparable. Fruits like these do not open, and are dispersed whole. The fruits of most compos- ites are crowned by the feather-like hairs which represent the calyx, and float on the breeze as thistledown or dandelion clocks (Figs. 42, 43, 44, 45). John-go-to-bed-at-noon, an English compos- ~WHAT PLANTS DO FOR THEIR YOUNG. 153 ite of the dandelion type, has a very remarkable and highly-developed parachute of this descrip- tion. In the anemones and clematis the fruit consists of several distinct one-seeded carpels, each furnished with a long feathery awn for the purpose of floating ; our common English clematis or traveller's joy, when in the fruiting condition, is known on this account as " old man's beard." Floating fruits like these, or those of many sedges 154 THE STORY OF THE PLANTS. and grasses, will often be carried by the wind for miles together. A well-known example of this type is the sedge commonly though wrongly de- scribed as cotton-grass. In other instances it is the seed, not the fruit, that is winged or feathered. The pod of the wil- low opens at maturity, and allows a large number of cottony seeds to escape upon the breeze. The same thing happens in the beautiful rose-bay and the other willow-herbs. Cotton is composed of the similar floating hairs attached to the seeds of a sub-tropical mallow-like tree. You will have observed, however, that not one of the fruits which I have hitherto mentioned is a fruit at all in the common or popular acceptation of the word. They are only at best what most people call pods or capsules. A true fruit, as most people think of it, is coloured, juicy, pulpy, sweet, and edible. How did such fruits come into exist- ence, and what is the use of them ? Well, just as certain plants desire to attract insects to fertilise their flowers, so do other plants desire to attract birds and beasts to disseminate their fruits for them. If any fruit happened to possess a coloured and juicy outer coat, or to show any tendency towards the production of such a coat, it would sooner or later be eaten by animals. If the animal digested the actual seed, however, so much the worse for the plant, and we shall see by and by that most plants take great care to prevent their true seeds being eaten and assimi- lated by animals. But if the seed was very small and tough, or had a stony covering, it would either be passed through the animal's body undigested, or else thrown away by him when he had finished WHAT PLANTS DO FOR THEIR YOUNG. 155 eating the pulpy exterior. So, many plants have acquired fruits of this description edible fruits, intended for the attraction of birds and animals. As a rule the animals disperse the seeds in the well-manured soil near their own nests or lairs, so that the young plants produced from such fruits start in life under exceptional advantages. Fruits that seek to attract animals use much the same baits to allure them in the way of colour and sweet taste as do the flowers that seek to at- tract insects. But just as almost any part of the flower may be brightly coloured, so almost any part of the fruit may be sweet and pulpy. Thus we get an astonishing and rather embarrassing variety of special devices in this matter. A few instances must suffice us. In the rasp- berry and blackberry the fruit consists of sepa- rate carpels, in each of which the outer coat be- comes soft and sweet, while the actual seed is hard and nut-like. In the one case the fruit is red, in the other black, but very conspicuous among the green leaves in autumn. These ber- ries are eaten by birds, and their seeds are dis- persed in copse or hedgerow. But in the straw- berry, which is a near relation of both, with a very similar flower, the actual carpels remain to the end quite small and seed-like; they are the tiny hard objects scattered about in pits like miniature nuts over the surface of the ripe berry. Here it is the common receptacle of the fruit that swells out and reddens, the part answering to the central piece which comes out whole in the middle of the raspberry ; so that what we eat in the one fruit is the very same part as what we throw away in the other. In the plum, the cherry, and the peach, on the other hand, there is but one carpel, and its 156 THE STORY OF THE PLANTS. outer covering grows soft, sweet, and brightly col- oured ; while the actual seed, though soft, is con- tained in a hard and stony jacket, an inner layer of the fruit coat. Here the true seed is what we call the kernel, but it is amply protected by its bone- like coverlet. In the apple and pear the ovary is inferior; the fruit is thus crowned by the remains of the calyx ; if you cut it across you will find it consists of a fleshy part, which is the swollen stem, enclosing the true fruit or core, with a number of seeds which we call the pips. All these fruits be- long to the family of the roses ; they serve to show the immense variety of plan and structure which occurs even in closely related species. Other suc- culent fruits of the same family are the rose-hip, the haw, the medlar, and the nectarine. Among familiar woodland fruits dispersed by birds I may mention the elderberry, the dogwood, the honeysuckle, the whortleberry, the holly, the cuckoo-pint, the barberry, and the spindle-tree. The white berries of the mistletoe, which is a parasitic plant, are eaten by the missel-thrush, a bird who has a special affection for this particu- lar food. But they are very sticky, and the seeds therefore adhere to the bird's beak and feet. To get rid of them, he rubs them off on the fork of a poplar branch, or in the bark of an apple-tree, which are the exact places where the mistletoe most desires to place itself. Many such close correspondences between bird and fruit exist in nature. Our northern berries are chiefly designed to be eaten by small birds like robins and hawfinches. But in southern climates larger fruits exist, adapted to the tastes of larger animals such as parrots, toucans, hornbills, fruit-bats, and mon- WHAT PLANTS DO FOR THEIR YOUNG. 157 keys. Our own small kinds can generally be eaten whole, like the currant and the strawberry; but these large southern fruits have often a bitter or unpleasant or very thick rind, which the birds or monkeys, for whose use they are intended, know how to strip off them. Cases in point are the orange, the lemon, the shaddock, the banana, the pine-apple, the mango, the custard-apple, and the breadfruit. The melon, cucumber, pumpkin, FIG. 46. FIG. 47. FIG. 48. Adhesive fruits. Fig. 46, of houndstongue. Fig. 47, of cleavers. Fig. 48, of herb-bennet. gourd, vegetable marrow, and water-melon are other southern forms cultivated in the north for the sake of their fruits. In the pomegranate the fruit itself is a dry capsule, but the seeds are each enclosed in a separate juicy coat. The grape is a fruit too well known to require detailed de- scription. As flowers sometimes club together, so also do fruits. In the mulberry the apparent berry is really made up of the distinct carpels of several separate flowers, which grow together as they 158 THE STORY OF THE PLANTS. ripen ; while the fig is a hollow stalk, in which numerous tiny fruits, commonly called seeds, are closely embedded. In all these cases animals act as willing agents in the dispersal of fruits or seeds. But some- times the plant compels them to carry its seeds against their will. Thus the fruits of the hounds- tongue (Fig. 46) consist of four small nuts, covered with hook-like prickles, which cling to the coats of sheep or cattle. The beasts rub these annoy- ing burdens off against bushes or hedges, and so disseminate the seeds in suitable places for ger- mination. The double fruit of cleavers (Fig. 47) is also supplied with similar prickles, while that of herb-bennet (Fig. 48) has a long curved awn which makes it catch at once on any passing animal. There are a large number of fruits, however, w r ith richly stored seeds, which desire rather to escape the notice of animals, some of whom, like squirrels and dormice, try to make their living out of them. These we call nuts. Their tactics are the exact opposite of those pursued by the edible fruits. For the edible fruits strive to attract animals to disperse them; the nuts, on the contrary, having the actual seed richly stored with oils and starches, desire to protect it from being eaten and destroyed. Hence they are generally green when on the tree, so as to escape notice, and brown when lying on the ground beneath it. Cases of these protectively- arranged fruits, with hard shells and often with nauseous external coverings (some of which are not regarded as nuts in the strict botanical sense), are the walnut, the hazel-nut, the coco- WHAT PLANTS DO FOR THEIR YOUNG. 159 nut, the chestnut, the acorn, the lime-nut, the almond, and the hickory-nut. In the Brazil nut the seeds (which are what we commonly call the nuts) are enclosed in a solid shell like that of a coco-nut, and are themselves also hard and nut- like. In the chestnut the fruit is a prickly cap- sule, inside which lie the seeds, which we know as chestnuts. But why have some plants so many seeds and some so few ? Well, the simpler and earlier types produce a very large number of ill-pro- vided seeds, which they turn loose upon the world to shift for themselves almost from the outset. Many of them perish, but a few survive. On the other hand, the more advanced plants, as a rule, produce only a small number of seeds, but each of these is well provided with starches and oils for the growth of the young plant ; and as most such survive, any tendency in the direc- tion of laying by food-stuffs would of course be favoured by natural selection. Just so among animals, a codfish produces nearly a million eggs, of which only two or three on an average survive to maturity ; while a bird produces half a dozen large and well-stored eggs, and a cow or a horse rarely brings forth more than one calf or foal at a birth. Decrease in the number of seeds is a fair rough test of relative progress. In nuts, you can see at once, the seeds are very richly stored, and the young plant starts in life, able to draw for a time on these ready-made food-stuffs, until its green leaves are in a position to lay by starches and protoplasm in plenty for it. It draws by degrees upon the accumulated materials. Such plants are like capitalists who 160 THE STORY OF THE PLANTS. can start their sons well in life with a good be- ginning. On the other hand, the poppy has to set out on its career with a very poor equipment ; it must begin picking up carbonic acid for itself almost from the outset. Such plants are like street arabs, compelled to shift as best they can from their earliest days. A coco-nut starts so well that the young palm can grow to a consider- able size without working for itself ; so to a less degree do walnuts, hazels, and oak-trees. Among other sets of plants there are two great groups which have especially learned to lay by foods for their seedlings the peaflower family and the grasses. In both these cases the young plants start in life with exceptional advantages. But what will feed a young plant will also feed an animal. Hence men live largely in different countries off such richly-stored seeds among nuts, the coco-nut, the chestnut, and the walnut ; among peaflower seeds, the pea, the bean, the vetch, the lentil ; among grasses, wheat, rice, barley, Indian corn, rye, millet. Recollect, however, that in all these cases the plant does not desire the seed to be eaten. It stored the tissues richly for its own sake and its offspring's alone, and we come and rob it. So, too, with the edible roots or tubers, such as potatoes, yams, turnips, beet-root, and so forth ; the plant meant to use them for its own future growth ; man appropriates them and disappoints its natural expectations. It is quite different with the succulent fruits, like the date and the plantain, which form in many countries the staple food of great populations ; nature meant those to be eaten by animals, and offered the pulp in re- turn for the benefit of dispersion. THE STEM AND BRANCHES. 161 Finally, when the seed is put into the ground and exposed to warmth and moisture, it begins to germinate. This it does by sending up a small growing shoot towards the light, which soon de- velops green leaves; as well as by sending down a root towards the earth, which soon begins to suck up water, together with the dissolved nitroge- nous matter. That is the beginning of a fresh plant-colony, which thus owes its existence to two separate individuals, a father and a mother. The seed consists of two first seed-leaves in the five- fold plants, as you can see very well in a sprout- ing bean, and of one such seed-leaf in the three- fold division, as you can see very well in a sprout- ing grain of wheat, or, still better, a lily seed. These earliest leaves are technically known as seed-leaves or cotyledons, and that is why the five- fold plants are known to botanists by the awk- ward name of dicotyledons, while the threefold are called monocotyledons. These names mean merely plants with two or with one seed-leaf. CHAPTER XII. THE STEM AND BRANCHES. You may have observed that so far I have told you a good deal about leaves and roots, flow- ers and seeds, but little or nothing about the na- ture of the stems and branches that bear them. I have done this on purpose; for my object has been to give you as much information at a time as you could then and there understand, building up by degrees your conception of plant economy. 1 62 THE STORY OF THE PLANTS. Now, leaves and flowers are, so to speak, the units of the plant-colony, while stem and branches are the community as a whole and the mode of its organisation. You must know something about the component parts before you can get to under- stand the whole built up of them ; you must have seen the individual citizens themselves before you can comprehend the city or nation composed by their union. The stem, then, is the part of the plant-colony which does not consist of individual leaves, either digestive or floral, but which binds them all to- gether, raises them visibly to the air, and supplies them with water, nitrogenous matter, and the re- sults of previous assimilation elsewhere. The stem and branches are common property, as it were ; they belong to the community : they repre- sent the scaffolding, the framework, the canals, the roads, the streets, the sewers, of the com- pound plant-colony. How did stems begin to exist at all ? The most probable answer to that question we owe, not to any professional botanist, but to our great philosopher, Mr. Herbert Spencer. The simplest and earliest plants, we saw, were mere small floating cells, endowed with active chlorophyll. Next in the upward order of evolu- tion came rows of such cells, arranged in long lines, like hairs or threads, or like pearls in a neck- lace, as in the green ooze of ponds and lakelets. Above these simple plants, again, come flat ex- panded collections of cells, as in the fronds of seaweeds. Now, all these kinds of plant are stem- less. But suppose in such a plant as the last, one frond or leaf took to growing out of the middle of another, as it actually does in many instances, THE STEM AND BRANCHES. I6 3 we should get the beginning of a compound plant, many-leaved, and with a sort of early or nascent stem, formed by the part that was common to many of the leaves, like a midrib. The accom- panying diagram (Fig. 49) will make this clear- er than any amount of description could pos- sibly make it. Start- ing from such a point, certain plants would soon find they were thus enabled to over- top others, and to ob- tain freer access to FlG . 49 ._ First steps in the evoiu- 1 ight and carbonic acid. tion of the stem. Gradually, natural se- lection would ensure that the common central part of the growing plant, the developing stem, should become harder and more resisting than the rest, so as to stand up against the wind and other oppos- ing forces. At last there would thus arise a clearly-marked trunk, simple at first, but later on branching, which would lift the leaves and flowers to a considerable height, and hang them out in such a way as to catch the sunlight and air to the best advantage, or to attract the fertilising insects or court the wind under the fairest conditions. I leave you to think out for yourself the various stages of the process by which natural selection must in the end secure these desirable objects. In order to understand the nature of the stem, in its fully developed form, however, we must re- member that it has three main functions. The 164 THE STORY OF THE PLANTS. first is, to raise the foliage, with the flowers and fruits as well, visibly above the surface of the ground on which they grow, so that the leaves may gain the freest possible access to rays of sun- light and to carbonic acid, while the flowers and fruit may receive the attentions of insects and birds, or other fertilising and distributing agents. The second is, to conduct from the root to the fo- liage and other growing parts what is commonly -called the raw sap that is to say, the body of water absorbed by the rootlets, together with the nitrogenous matter and food-salts dissolved in it, .all of which are needed for the ultimate manu- facture of protoplasm and chlorophyll. The third is, to carry away and distribute the various ma- tured products of plant life, such as starches, .sugars, oils, and protoplasm, from the places in which they are produced (such as the leaves) to the places where they are needed for building up the various parts of the compound organism (such as the flowers and fruit or the growing shoots), as well as to the places where such materials are to be stored up for safety or for future use (as, for example, the tubers and roots, or the buds, bulbs, and other dormant organs). Each of these three essential functions we must now proceed to con- sider separately. In order to raise the leaves and branches visi- bly above the ground into the air above it, the stem is made much stronger and stouter than the ordinary leaf-tissue. If the plant does not rise very high above the ground, indeed, as in the case of. small herbs, and especially of annuals, its stem need not be very hard or stiff, and is often in point of fact quite green and succulent. But THE STEM AND BRANCHES. 165, just in proportion as plants grow tall and spread- ing, carry masses of foliage, and are exposed to- heavy winds, do they need to form a stout and woody stem, which shall support the constant weight of the leaves, or even bear up under the load of snow which may cover the boughs in win- try weather. Thus, a tapering tree like the Scotch fir requires a comparatively smaller stem than an oak, because its branches do not spread far and wide, while its single leaves are thin and needle- like; whereas the oak, with its massive boughs- extending far and wide on every side, and cov- ered with a weight of large and expanded absorb- ent leaves, requires a peculiarly thick and but- tressed stem to support its burden. Both in girth and in texture it must differ widely from the loose and swaying pine-tree. Every stem is thus a piece of ingenious engineering architecture, adapt- ed on the average to the exact weight it will have to bear, and the exact strains of wind and weather to which on the average it may count upon being exposed in the course of its life-history. We see the result of occasional failure of adaptation in this respect after every great storm, when the corn in the fields is beaten down by hail, or the fir-trees in the forest are snapped off short like straw by the force of the tempest. But the sur- vivors in the long run are those which have suc- ceeded best in resisting even such unusual stresses ; and it is they that become the parents of after generations, which of course inherit their powers of resistance. Most stems, at least of perennial plants, and all those of bushes, shrubs, and forest trees, are strengthened for the purpose of resisting such strains by means of a material which we call 166 THE STORY OF THE PLANTS. wood. And what is wood ? Well, it is an ex- tremely hard and close-grained tissue, manufac- tured by the plant out of its ordinary cells by a deposit on their walls of thickening matter. This process of thickening goes on in each cell until the hollow of the centre is almost entirely filled up by the thickening material, leaving only a small vacant space in the very middle. The thickening matter, which consists for the most part of carbon and hydrogen, is built up there by the protoplasm of the cell itself: but as soon as the process is quite complete, the protoplasm emigrates from the cell entirely, and goes to some other place where it is more urgently needed. Thus wood is made up of dead cells, whose walls are immensely thickened, but whose living con- tents have migrated elsewhere. In large perennial stems, like those of oaks and elms, a fresh ring of wood is added each year outside the ring of the last growing season. This new ring of wood is interposed between the bark (of which I shall speak presently) and the older wood of the core or heart, which was simi- larly laid down when the tree was younger. In this way, the number of rings, one inside another, enables us roughly to estimate the age of a tree when we cut it down ; though, strictly speaking, we can only tell how many times growth in its trunk was renewed or retarded. Still, as a fair general test, the number of rings in a trunk give us an approximate idea of the age of the indi- vidual tree that produced it. The principle is only true, however, of the great group of dicotyledonous trees, such as beeches or ashes, as well as of the pines and other coni- fers. In monocotyledonous trees, like the palms and THE STEM AND BRANCHES. 167 bamboos, the stem does not increase in quite the same way from within outward, and there are therefore no rings of annual growth to judge by. Palms rise from the ground as big or nearly as big at the beginning as they will ever be in the end ; and though each year they rise higher and higher into the air, and produce a fresh bunch of leaves at their summit, they seldom branch, and they never produce large buttressed stems like the oak or the chestnut. The second main function of the stem is to convey the raw sap absorbed by the roots to the leaves and branches, and especially to the grow- ing points. This is such a very important element in plant life that we must now consider it in some little detail. If you look for a moment at a great spreading oak-tree, with its top rising forty or fifty feet above the level of the ground, and its roots spreading as far and as deep beneath the earth, you will see at once how serious and difficult a mechanical problem it is for the plant to raise up water from so great a depth to so great a height without the aid of pump or siphon. For the plant can no more work miracles than you or I can. Yet every leaf must be constantly supplied with water, that prime necessary of life, or it will wither and die ; and every growing part must ob- tain it in abundance, in order to give that plas- ticity and freedom which are needful for the earlier constructive processes. Protoplasm itself can ef- fect nothing without the assistance of water as a solvent for all materials it employs in its opera- tions. How does the plant get over these difficulties ? 1 68 THE STORY OF THE PLANTS. Well, the stem is well provided with a whole sys- tem of upward distributing vessels in which water may be conveyed to the various parts, just as it is conveyed in towns through the pipes and taps wherever it is needed. But what is the motive power for this mechanical work ? How does the plant raise so much liquid to such a considerable height, without the intervention of any visible and tangible machinery ? Two main agents are employed for this pur- pose. The one is known as root-pressure ; the other as evaporation. I begin with the former. The cells of which roots are made up are most ingeniously constructed so as to exert this peculiar form of pressure. Each one of them has at its outer or free end, where it comes into contact with the moist earth, a wall of such a nature, that it very readily ab- sorbs water, and allows the water so absorbed to flow freely through it inward. But once in, the water seems almost as if imprisoned in a pump; it cannot pass outward again, only inward and upward. You may compare the cell in this respect w r ith those mechanical valves which yield readily to the pressure of fluids from outside, but instantly close when a fluid from inside attempts to pass through them. In this way the outer cells of the hairs on the roots, which come in contact with the moistened soil, get distended with water, and swell and swell, till at last their walls will give no long- er, and their own elasticity forces the water out of them. But the water cannot flow back ; so it has to flow forward. Again, each cell or vessel which the stream afterwards enters is construct- ed on just the same general principle as the ab- sorbent root-cells ; it allows water to pass into it THE STEM AND BRANCHES. 169 freely from below upward, but does not allow it to pass back again from above downward. Thus we get a constant state of what is called turgidity in the lower cells; they are as full as they can hold, and they keep on contracting elastically, so as to expel the water they contain into other cells next in order above them. By means of such root-pressure, as it is called, raw sap is being for ever forced up from the soil beneath into the stem and branches, to supply the leaves with water and food-salts, especially in early spring, when the processes of growth are most active and vigorous. It is owing to this peculiar property of root- pressure that cut stems " bleed " or exude sap, especially in spring-time. The root-pressure con- tinues of itself in spite of the fact that the stem has been divided ; and the sap absorbed by the roots is thus forced out at the other end by the continuous elasticity of the cells and vessels. The fact that severed stems will thus " bleed " or exude raw sap shows in itself the reality of root- pressure. But root-pressure alone would not fully suffice to raise so large a body of water as the plant re- quires to so great a height above the earth's sur- face. It is therefore largely supplemented and assisted by the second or subsidiary power of evaporation. This evaporation, or " transpira- tion " as it is generally called, is just as necessary and essential to plants as breathing is to men and animals. We must therefore enter a little more fully here into the nature of so important and universal a plant function. You will remember that when we were discussing the nature of leaves, I gave 170 THE STORY OF THE PLANTS. you a woodcut of a thin slice through a leaf (Fig. i) which showed the blade as naturally divided into an upper and under portion. The upper por- tion consisted of very close-set green cells, con- taining living chlorophyll, and covered by a single transparent water-layer, which absorbed carbonic acid from the air about, and passed it on to be digested by the living chlorophyll-layer just be- neath it. But the under portion was sparse-look- ing and spongy ; it was composed of cells loosely arranged among themselves, and interspersed with great empty spaces. I told you but little at the time of the function or use of this lower portion ; we must return to it now in the present connec- tion, as a component element in the task of water- supply. The lower portion of most leaves is the part employed in the great and necessary work of evaporation. For this purpose the tissue at the under side of the leaf is composed of loose and spongy cells which have much of their surface exposed to the empty spaces between them : and these emp- ty spaces are really air-cavities. The object of the cavities, indeed, is to facilitate evaporation, Liquid transpires into them from the various cells through the wall that bounds them. How fast water evaporates in the leaves of plants we all know by experience in a thousand ways. We know, for instance, that if we pick bunches of flowers and leave them in the sun without water, they fade and dry up in a very short time. We also know that if we forget to water plants in pots, the plants similarly dry up and die after a few hours' exposure. Leaves, in fact, are pur- posely arranged in most cases so as to encourage THE STEM AND BRANCHES. 171 a very rapid evaporation ; and evaporation is one of their chief means of raising water from the roots to the growing and living portions. If you examine the under side of a leaf under the microscope, you will find it is covered by hundreds of little pores which look exactly like mouths, and which are guarded by two cells whose resemblance to lips is absurdly obvious. These pores are commonly known to botanists by the awkward name of stomata, which is the Greek for mouths; and mouths they really are to all exter- nal appearance. You must not suppose, however, that they are truly mouths in the sense of being the organs with which the plant eats ; the upper surface of the leaf, as we saw, with its layer of water-cells and its assimilating chlorophyll-bodies, really answers in the plant to our mouths and stomachs. The stomata or pores are much more like the openings in the skin by which we per- spire ; only perspiration or evaporation is an even more important part of life to the plant than it is to the animal. Each of the stomata opens into an air-cavity ; and through it the liquid evaporated from the cells passes out as vapour into the open air. Many leaves have thousands of such pores on their lower surface ; they may easily be rec- ognised under the microscope by means of the curious guard-cells which look like lips, and which give the pores, in fact, their strange mouth-like aspect. What is the use of these lips? Well, they are employed for opening and closing the evaporat- ing pores, or stomata. In dry weather it is not desirable that the pores should be open, for then evaporation should be limited as far as possible. So, under these conditions, the lips contract, and 172 THE STORY OF THE PLANTS. the pore closes. Excessive evaporation at such times would, of course, damage or destroy the foliage ; the plant desires rather to store up and retain its stock of moisture. But after rain, and in damp weather, the roots suck up abundant water; and then it becomes desirable that evapo- ration should go on, and the leaves and grow- ing shoots should be supplied with liquid food, as well as with the nitrogenous matter and salts dissolved in it. Hence at such times the pores open wide, and allow the water in the form of vapour to exude from them freely. The object of this evaporation, again, is two- fold. In the first place, it supplements root- pressure as a means of raising water to the leaves and growing shoots; and in the second place, by getting rid of superfluous liquid, it leaves the nitrogenous material and the food-salts in a more concentrated form, at the very points where they are just then needed for the formation of fresh liv- ing protoplasm and other useful constructive fac- tors of plant-life. But how does evaporation raise water from the ground ? In this way. The liv- ing contents of each cell on the upward path have a natural chemical affinity for water, and will suck it up greedily wherever they can get it. Thus each part, as fast as it loses water by evaporation, takes up more w'ater in turn from its next neighbour below ; and that once more withdraws it from the cell beneath it ; and so on step by step until we reach the actual absorbent root-hairs. Root-pressure by itself could not raise water as high as we often see it raised in great forest trees and tropical climbers ; it has not enough mechanical motor power. But here evaporation comes in, to aid it in its task ; and THE STEM AND BRANCHES. 173 the real motor power in this last case is the very potent force of chemical attraction. What I have said here about evaporation, and the way it is conducted by means of pores on the surface of the leaves, is true of the vast majority of green plants ; but considerable varieties and modifications occur, of course, in accordance with the necessities of various situations. For example, the brooms and many other shrubs of the same twiggy type have few green leaves, but in their stead produce lithe green stems, filled with active chlorophyll. These stems and branches do all the work usually performed by ordinary foliage. Stems and twigs of this type are cov- ered with mouth-like pores, or stomata, in exactly the same way as the under side of leaves in most other species. Similarly, the very flattened leaf- like branches of the butcher's broom, and of the Australian acacias and other Australasian trees, are well supplied with like pores for purposes of evaporation. Again, while the pores are usually found on the under surface of the leaf, they are situated on the upper surface of leaves which float on water, like the water-lily and the water-crow- foot ; because in such plants they would be obvi- ously useless for purposes of evaporation on the lower side, which is in contact with the water. Some leaves have the stomata on both sides alike, especially when no one side is much more ex- posed to sunlight than another. But wherever t they are found, they always lie above masses of loose and spongy cell-tissue, in whose meshes and air-spaces evaporation can go on readily. On the other hand, as I noted before, leaves which grow in very dry or desert situations re- quire as much as possible to curtail evaporation. 174 THE STORY OF THE PLANTS. Such leaves are therefore usually thick and fleshy, and possess a very small allowance of pores. The forms of several leaves, again, are largely de- pendent upon the necessity for keeping the pores free from wetting, and promoting evaporation whenever it is needful for the plant's health and growth ; and this is particularly the case with what are called " rolled leaves," such as one sees in the heaths and the common rock-roses. Many such additional principles have always to be taken into consideration in attempting to account for the various shapes of foliage : indeed, we can only rightly understand the form of any given leaf when we know all about its habits and its native situation. The stem, then, besides raising the leaves and flowers, for which purpose it is often strengthened by means of mechanical woody tissue, also acts as a conductor of raw sap from the tips of the roots to the leaves and growing points, for which purpose it is further provided with an elaborate system of canals and vessels, running direct from the absorbent root to all parts of the compound plant community. The third function of the stem and branches is to convey and distribute the elaborated prod- ucts of plant-chemistry and plant-manufacture from the places where they are made to the places where they are needed for practical pur- poses. We saw long since that starches, sugars, pro- toplasms, and chlorophyll are manufactured in the leaves under the influence of sunlight; and from the materials so manufactured every part of the plant must ultimately be constructed. But THE STEM AND BRANCHES. 175 we never said a word at the time about the means by which the materials in question were carried about and distributed to the various organs in need of them. Nevertheless, a moment's con- sideration will show you that new leaves and shoots must necessarily be built up at the expense of materials supplied by the older ones; that flowers, fruits, and seeds must be constructed from protoplasm handed over for their use by the neighbouring foliage. Nay more ; the root itself grows and spreads; and the very tips of the roots, which themselves of course can manufac- ture nothing, must be supplied from above with most active and discriminating protoplasm, to guide their movements. Whence do they get it ? From the factory in the foliage. Thus, from the summit of the tallest tree down to the lowest root that fastens it in the soil, there runs a com- plex system of pipes and tubes for the special conveyance of elaborated material ; and this sys- tem supplies every growing part with the food- stuff necessary for its particular growth, and every living part with the food-stuff necessary for maintaining its life and activity. An inter- change of protoplasmic matter, starches, and sugars, goes on continually through the entire organism. This downward and outward stream of living matter, carrying along with it live protoplasm and other foods or manufactured materials, must be carefully distinguished from the upward stream of crude sap which rises from the roots to the leaves and branches. The one contains only such raw materials of life as are supplied by the soil namely, nitrogenous matter, water, and food- salts ; the other contains the things eaten from 176 THE STORY OF THE PLANTS. the air by the plant in its leaves, and afterwards worked up by it into sugars, starches, protoplasm, and chlorophyll. Stems are usually covered outside for purposes of protection by a more or less thick integument, which in trees and shrubs assumes the corky form we know as bark. Bark consists of dead and empty cells, thickened with a lighter thickening matter than wood, and presenting as a rule a rather spongy appearance. But beneath the bark comes a distinct layer of living material, inter- posed between the corky dead cells of the integu- ment and the woody dead cells of the interior. This living layer extends over stem, twigs, and branches : it forms the binding and connecting portion of the entire plant community ; it links together in one united whole the living material of the leaves and shoots w r ith the living material of the roots and rootlets. It is thus the stem, above all, that gives to the complex plant colony of foliage and flowers whatever organic unity and individuality it ever possesses. All situations, however, are not alike. Just as here this sort of leaf succeeds, and there that, so in stems and branches, here this form does best, and there again the other. The shape of the stem and branches, in fact, is the shape of the entire plant colony ; and it is arranged to suit, on the average of instances, the convenience of all its component members. Much depends on the shape of the leaves ; much on the conditions of wind .or calm, shade or sunshine. Some plants are annuals. These require no large and permanent stem ; they spring from the THE STEM AND BRANCHES. 177 seed each year, like peas, or wheat, or poppies; they make a stem and leaves ; they produce their flowers ; they set, and ripen, and scatter their seed ; and then they wither away and are done with for ever. Hundreds of such plants occur in our fields and gardens. Even these annuals, how- ever, differ greatly in the amount of their stem and branches. Some are quite low, humble, and suc- culent, like chickweed and sandwort ; others have tall and comparatively stout stems, like wheat, oats, and barley, or still more, like the sunflower. As a rule, annuals are not very large ; but a few rich seeds produce strong young plants which even within a single year attain an astounding size ; this is the case with the garden poppy, the tobacco plant, and the Indian corn, and even more so with certain climbing annuals, such as the gourd, the cucumber, the melon, and the pumpkin. Many plants, however, find it pays them better to produce a hard and woody stem, which lasts from year to year, and enables them to put forth fresh leaves and shoots in each succeeding season. Among these, again, great varieties exist. Some have merely a rather short and stout stem with many bundles of water-vessels, as in the pink and the wallflower. Their growth is herbaceous. Others, however, produce that more solid form of tissue which we know as wood, and which is made up of cells whose walls have become much thickened and hardened. Among the woody group, again, we may distinguish many intermediate varieties, from the mere shrub or bush, like the heath and the broom, through small trees like the rhododen- dron, the lilac, the hawthorn, and the holly, to such great, spreading monsters of the forest as 178 THE STORY OF THE PLANTS. the oak, the ash, the pine, the chestnut, and the maple. Once more, some plants produce an under- ground stem, and send up from this fresh annual branches. That is the 'case with hops, with meadow-sweet, and with buttercup, as well as with many of our garden flowers. When a plant becomes perennial, it is a mere question of its own convenience whether it chooses to produce a thick and woody stem, like trees and bushes, or to lay up material in undergound roots, stocks, and branches, like the potato, the dahlia, the lilies, the bulbous buttercup, the crocus, the iris, the Jerusalem artichoke, and the meadow orchis. Ordinary people divide most plants into three groups herbs, shrubs, and trees. But I think you will have seen from what I have just said that in every great family of plants different kinds have found it worth while to adopt any one of these forms at will, according to circumstances. Trees, in other words, do not form a natural group by themselves; any family of plant may happen to develop a tree-like species. Thus the herb-like clover and the tall tree-like laburnum are closely related peaflowers. Most of the com- posites are mere herbs or shrubs, but a very few of them in the South Sea Islands have grown into large and much-branched trees. The grasses are mainly herbs ; but some of them, like the bam- boos, have developed tall and tree-like stems, much branched and feathery. Take the single family of the roses, for ex- ample, so familiar to most of us ; some of them are mtere annual weeds, like the tiny parsley-piert that occurs as a pest in every garden. Others, again, are perennials with low tufted stems, like the THE STEM AND BRANCHES. 179. strawberry; or creeping, like the cinquefoil ; or rising into a spike, like the burnet and the agri- mony. Yet others become scrambling bushes, like the blackberry and the raspberry. In the blackthorn and the hawthorn the bush has be- come more erect and tree-like. Both types of growth occur in the dog-rose and many other roses. The cherry attains the size and stature of a small tree. The mountain-ash is bigger ; the apple-tree bigger still ; while the pear often grows to a considerable height and much spread- ing dignity. These are all members of the rose family. Here, therefore, every variety of shape and size is well represented within the limits of a single order. One word must be given to the varieties of the stem. Sometimes, as in the oak, the trunk is- much branched and intricate; sometimes, as in the date-palm, simple and unbranched, bearing only a single tuft of circularly arranged leaves. But the most interesting in this respect are the climbing and twisting stems, which do not take the trouble to support themselves, but lean for aid upon the trunk of some stronger and more upright neighbour. Stems of this sort are familiar to us all in the hop and the bindweed. In other climb- ers the stems do not twine to any great extent, but the plants support themselves by root-like processes, as in ivy, or by tendrils, as in the vine, or by twisted leaf-stalks, as in the canary creeper. Others cling by means of suckers, as the Ampelop- sis Veitchii, or hang by opposite leaves, like clem- atis, or cling by hooked hairs, as is the case with cleavers. In certain instances, such creeping or climbing plants tend to become parasitic that is to say, they fasten themselves by sucker-like 180 THE STORY OF THE PLANTS. mouths to the bark of the harder plant up which they climb, and feed upon its already elaborated juices. Our English dodder is an example of such a plant. It has no leaves of its own, but consists entirely of a mass of red stems, bearing clusters of pretty pale pink flowers. Other plants show another form of parasitism. Mistletoe is one of these. It fastens itself to a poplar or an apple-tree (very seldom an oak) and sucks its juices. But it has also green leaves of its own, which do real work of eating and assimi- lating as well. It is therefore not quite such a parasite as the dodder. Several plants are simi- larly half-parasitic on the roots of wheat and grasses. Among them I may mention, as English instances, the cow-wheat, the yellow rattle, and the pretty little eyebright. Broomrape is a parasite of a different sort. It grows on the roots of clover, and has no true leaves ; in their place it produces short scales, which contain no chlorophyll. Several other plants are also devoid of chlorophyll, and there- fore cannot eat carbonic acid for themselves. They live like animals on materials laid by for them by other plants. Such are toothwort, a pale rose-coloured leafless plant, with pretty spiked flowers, which grows by suckers on the roots of ^hazel-trees. The bird's-nest orchid, a delicate brown plant with curious ghost-like blossoms, feeds rather on the organised matter in decaying leaves among thick beechwoods. In this book I have purposely confined your attention for the most part to the true green plants, which are the central and most truly plant-like type; but I ought to tell you now that a great many plants, especially among the lower kinds, behave in this THE STEM AND BRANCHES. l8l respect much more like animals: instead of manufacturing fresh starches and protoplasms for themselves from carbonic acid, under the in- fluence of sunlight, they eat up what has already been made by other and more industrious species. Such plants are retrograde. They are products of degeneracy. Among them I may specially mention all the fungi, like mushrooms, toadstools, mould, and mildew, as well as the bacilli and bac- teria, microscopic and degenerate plants which cause decomposition. Their life is more like that of animals than of true vegetables. In tropical forests, where the soil is almost monopolised by huge spreading trees, the smaller plants have been forced to secure their fair share of light and air by somewhat different means from those which are common in cooler climates. Many of them, without being parasitic, have learnt to attach themselves by their roots to the outer bark of the trees, and so to get at the light, no ray of which ever struggles through the living canopy of green in the dense jungle. These plants have green leaves, and eat for themselves; but they use the boughs of their host instead of soil to root themselves in. Such plants are technically known as epiphytes. This is the mode of Hfe of most of the handsome orchids cultivated in our conservatories. Now let us recapitulate. The stem unites the various parts of the plant the root, the leaves, the flowers, the fruit. It conducts water and nitrogenous matter from the soil to the foliage. It also carries the manufactured materials from the points where they are made to the points 182 THE STORY OF THE PLANTS. where they are wanted for the growth of fresh organs. It supports and raises the whole plant colony. Finally, it stores up material in drought or winter, which it uses for new branches, leaves, or flowers, when rain or spring or favourable conditions in due time come round again. CHAPTER XIII. SOME PLANT BIOGRAPHIES. WE have considered so far the various ele- ments which go to make up the life of plants how they eat and drink, how they digest and assimilate, how they marry and get fertilised, how they produce their fruit and set their seeds, final- ly how they are linked together in all their parts by stem and vessels into a single community. But up to the present moment we have con- sidered these elements in isolation only, as so many processes the union of which makes up what we call the life of an oak, or a lily, or a strawberry plant. In order really to understand how all these principles work together in prac- tical action, we ought to take a few specimen lives of real concrete plants, and trace them through direct, from the cradle to the grave, with all their vicissitudes. I propose, therefore, in this chapter to give you brief sketches of one or two such life- histories ; and I hope these few hints may encour- age you to find out many more for yourself, by personal study of plants in their native sur- roundings. " In their native surroundings," I say, since SOME PLANT BIOGRAPHIES. 183 all life is really, in Mr. Herbert Spencer's famous phrase, "adaptation to the environment;" and therefore we can only understand and discover the use and meaning of each part or organ by watching the plant in its own home, and among the general conditions by which it and its ances- tors have always been limited. It would be im- possible, for example, to see the use of the thick outer covering of the coconut (from which coco- nut matting is manufactured) if we did not know that the coconut palm grows naturally by the sea- shore in tropical islands, and frequently drops its fruits into the water beneath it. The nuts are thus carried by the waves and currents from islet to islet ; and the coconut palm, which is a deni- zen of sea-sand, owes to this curious method of water-carriage its wide dispersion among the coral-reefs of the Pacific. But a plant that is so dispersed must needs make provision against wetting, bruising, and sinking in the sea; and since only those coconuts would get dispersed over wide spaces of water which happened to possess a good coating of fibre, the existing plant has come to produce the existing nut as we know it richly stored with food for the young palm while it makes its first steps among the barren rocks and sand-banks, and well provided by its shaggy outer coat against the dangers of the sea, the reefs, and the breakers. Similarly, we could never understand the cactus except as a native of the dry plains of Mexico. Or again, there is an orchid in Madagascar with a spur containing honey at a depth of eighteen inches. Now, no European insect could possibly reach so deep a deposit ; but a Madagascar moth has a gigantic proboscis, exactly fitted for sucking the nectary 184 THE STORY OF THE PLANTS. and fertilising the flowers. Thus no plant can properly be understood apart from its native place; and I have therefore confined myself for the most part in these few brief life-histories to native British plants, whose circumstances and surroundings are known to everybody. As an example of a very simple and easy life- history, I will take first a little wayside weed, commonly known as whitlow-grass, but called by botanists, in their scientific Latin, Draba verna. This curious little herb is not a grass at all (as its name might make you think), but a member of the great family of the crucifers, succulent plants with four petals and six stamens in each flower, to which the cabbage, the turnip, the sea-kale, and many other well-known garden species be- long. But whitlow-grass is not a large and con- spicuous plant like any of these ; it is one of the smallest and shortest-lived of our British weeds. It has managed to carve itself out a place in na- ture on the dry banks and in clefts of rock during the few weeks in spring while such spots are as yet unoccupied by more permanent denizens. The herb starts from a very minute seed, dropped on the soil by the parent plant many months before, and patiently waiting its time to develop till win- ter frosts are over, and warmer weather and moisture begin to quicken its tiny seed-leaves. As soon as these have opened and used up theii very small stock of internal nutriment, the young plant begins to produce on its own account a rosette of little oblong green leaves, pressed close to the ground for warmth and shelter. They eat as they go, and make fresh leaves again out of the absorbed and assimilated material. Direct sunshine falls upon them full front; and as no SOME PLANT BIOGRAPHIES. 185 other foliage overshadows them or competes in their neighbourhood for carbonic acid, they grow apace into a little tuft of spreading leaves, about half an inch long or less, and forming in the mass a rough circle. For about a week or ten days the little mouths go on drinking in carbonic acid as fast as they can, and manufacturing it under the influence of sunlight into starches and proto- plasm. At the end of that time they have col- lected enough material to send up a slender blos- soming stem, about an inch high or more, bearing no leaves, but developing at the top a few tiny flower-buds. These shortly open and display their flowers, very small and inconspicuous, with four wee white petals, each so deeply cleft that they resemble eight to a casual observer. Inside the petals are six little active stamens ; and inside the stamens again a two-celled ovary. The blos- soms are visited and fertilised on warm March mornings by small spring midges, attracted by the petals. They immediately set their seeds in tne flat green capsule, ripen them rapidly in the eye of the sun, and shed them at once, the whole life of the plant thus 'seldom exceeding three or four weeks in a favourable season. At the same time, the leaves and roots wither, as the material they contained is rapidly withdrawn from them, and used up in the process of maturing the seeds ; so that as soon as the fruiting is quite complete, the plant dies down, having exhausted itself ut- terly in the tw r o short acts of flowering and seed- bearing. During the remaining ten months o.f the year or thereabouts, there are no more whit- low-grasses at all in existence; the species re- mains dormant, as it were, for a whole long pe- riod in the form of seeds lying buried in the soil, 1 86 THE STORY OF THE PLANTS. and only springs to life again when the return of March gives it warning that its day has once more come round to it. Contrast with this brief and very spasmodic life of some thirty days the comparatively long though otherwise extremely similar biography of the Mexican agave, commonly cultivated in hot- houses in England, and largely grown in the open air in the South of Europe under the (incorrect) name of "American aloes." The agave is a large and strikingly handsome lily of the amaryllis fam- ily, about which I have already told you something in a previous chapter. It begins life as a small plant, like a London pride, springing from a com- paratively large and richly-stored seed on its own dry prairies. Its leaves, which spread in a rosette, are not unlike those of the house-leek in shape ; they are very large, thick, and fleshy. But as they grow in the hot and dry climate of Mexico, an almost desert country, with a very small rainfall, they have a particularly hard outer skin, so as to prevent undue evaporation ; and they are pro- tected against the attacks of. herbivorous animals by being spiny at the edges, and ending in a stout and dagger-like point of the most formidable de- scription. The centre of the plant is occupied by a sort of sheath of leaves, concealing the growing point. For several years the round bunch of outer leaves grows bigger and bigger, till it attains a diameter of ten or fifteen feet at the base, seem- ing still like a huge rosette, with hardly any visi- ble stem to speak of. Meanwhile these huge leaves are busy all the time, eating and assimilating, and storing up manufactured food-stuffs as hard as they can in their thick and swollen bases. After six or seven years in their native climate, the SOME PLANT BIOGRAPHIES. 187 plant feels itself in a position to send up a flower- ing stalk, which is formed from the materials al- ready laid by in these immensely thick and richly- stored leaf bases. The stalk springs from the middle of the central leaf-sheath. In a very few weeks the agave has sent up from this point a huge flowering scape, twenty or thirty feet high, and a foot or fifteen inches thick at the bottom. On this scape it produces with extraordinary ra- pidity a vast number of large and showy yellow flowers, which look not unlike an enormous can- delabrum, with many divided branches. The plant is enabled to produce this immense flowering stem and these numerous flowers in so short a period, because it draws upon its large store of elaborated material for the purpose. But as the flowering stem rises, and the flowers unfold, and the big fruits and seeds develop and ripen, the leaves be- low grow gradually flaccid and empty ; and their bases shrink, being depleted of their store of valu- able food-stuffs ; so that by the time the seeds are ripe, the whole plant is used up, having exhausted itself, like the tiny whitlow-grass, in the act of fruiting. It then dies down altogether, and never recovers, though new plants or offsets usually de- velop at its base from side buds, after the original agave has begun to wither. In English hothouses it takes thirty or forty years before the agave has collected enough material to send up a stem and flower; hence the common exaggeration that it needs a hundred years for " the blossoming of an aloe." As a familiar example of a very different kind of perennial plant, we may take our English beech- tree. The beech sets out in life as a tender young seedling, which grows from a good-sized triangular 1 88 THE STORY OF THE PLANTS. nut, whose cotyledons are well-stored with food- stuffs for its early development. As the nut ger- minates, the cotyledons open out, become flat and green, like thick fleshy leaves, and begin to absorb carbonic acid from the air, which they work up at once with the material supplied by the tiny root into protoplasm and chlorophyll. In the angle between them a young shoot develops, which soon puts forth delicate blades of true foliage leaves; and these in turn grow and assimilate material under the influence of sunlight. In the first year the little beech-tree is but a tiny sapling, with a short stem, already woody ; but year after year, this stem grows higher, branches out and divides, and slowly clothes itself in the smooth grey bark characteristic of the species. The particular way in which it branches is this : each autumn there is formed at the base of every leaf a winter bud, long and brown, and covered with close scales, which enable it to survive the cold of winter. When spring comes round again, each one of these buds develops in turn into a leafy branch, so that (accidents excepted) there are as many new branches or twigs every year as there were leaves on the tree in the preceding season. The young leaves and branches emerge slowly and cautiously from the buds in spring, for fear of frost ; they are protected at first by certain scaly brown coverings known as stipules. Gradually, however, as the weather grows warmer, the stip- ules fall off, and display the tender green leaves, exposed to the air, but still folded together. As soon as they can trust the season, however, the leaves unfold, though they are still thickly covered at the edges by protective hairs, which afterwards fall off, but which guard the fresh green chloro- SOME PLANT BIOGRAPHIES. 189 phyll in the cells just at first both from chilly winds and from the injurious effect of excessive sunlight. Year after year the beech-tree grows by so subdividing and adding branch to branch ; while its stem increases by yearly rings of growth, till it attains at length considerable dimensions. During many such seasons of growth the beech-tree does not flower; all the material it manufactures through the summer in its large flat leaves it lays by in its stem to supply the young shoots and branches at the beginning of the subsequent season. But at last, when it has reached the height and girth of a small tree, it begins to store up protoplasm and starches for blossom also. Some of its buds are now leaf- buds, but some are flower-buds, produced in autumn, and held over till April. In the spring these flower-buds lengthen and produce bunches of blossoms, which we call catkins, some of them males, and some females, but both sexes growing on the same tree together. They bloom, like most other catkins, in the early spring, while the leaves are still very little developed, so as to pre- vent the foliage from interfering with the carriage of the pollen. The males are produced in hang- ing clusters an inch or so long; while the females stand up in small globular bunches, on erect flower -stems. They are wind - fertilised ; and shortly after flowering, the male catkins drop off entire, having done their life-work, while the females swell out into the familiar husks or four- valved cups, containing each some two or three triangular nuts, richly stored with food-stuffs. The agave only flowers once, and then dies down, exhausted. But the beech goes on flower- ing for many years together, and grows mean- 1 90 THE STORY OF THE PLANTS. while larger and larger in bulk, its trunk increas- ing in girth, and becoming buttressed at the base, so as to support the large head of branches and the dense mass of foliage. For the boughs are so arranged that a great crown of leaves is ex- posed in summer to the sun and air at the outer circumference of the dome-shaped mass ; and in this way every leaf gets its fair share of light and carbon, and interferes as little as possible with the work of its neighbours. Old beeches will grow to more than 100 feet in height, and live for probably three or four centuries. At last, however, their protoplasm grows old and seems to get enfeebled ; the trunk decays, and the entire tree falls first into dotage, then dies by slow de- grees of pure senility. The common vetch is another familiar plant whose life-history introduces to us some totally different yet interesting features. It belongs to the wide-spread family of the peaflowers, to which I have already more than once alluded, and it takes its origin from a comparatively large and rich round seed, not unlike a pea, whose cotyle- dons are well stored with supplies of starch and other food-stuffs. It sends up at first a short spreading stem, which twines or trails over sur- rounding plants, developing as it goes very curi- ous leaves of a compound character. Each leaf consists of five or six pairs of leaflets, placed op- posite one another on the common stalk in the feather-veined fashion. But the four or five leaf- lets at the end of each leaf-stalk do not develop any flat blade at all, and are quite unleaflike in appearance : they are transformed, indeed, into long, thin tendrils, which catch hold of neigh- bouring branches or stems of grasses, twine SOME PLANT BIOGRAPHIES. 191 spirally round them, and so enable the vetch to climb up bodily in spite of its weak stem, and raise its leaves and flowers to the air and the sunlight. At the base of every leaf, again, you will find, if you look, two arrow-shaped appendages, which block the way up the stem towards the developing flowers for useless creeping insects such as steal the honey without assisting fertilisation. On each appendage is a curious black spot, the use or function of which is not apparent while the blos- soms are in the bud. But after a few weeks' growth, the vetch begins to produce solitary flowers in the angle of each upper leaf ; flowers of the usual pea-blossom type, but pink or red- dish purple, and handsome or attractive. These flowers contain abundant honey to allure the proper fertilising insects. Just as they open, however, the black spot on the arrow-headed appendages of the lower leaves, in whose angles there are no flowers, begins also to secrete a little drop of honey. What is the use of this device ? Well, if you watch the vetch carefully, you will soon see that ants, enticed by the smell of honey in the open- ing flowers, crawl up the stem in hopes of steal- ing it. But ants, as we know, are thieves, not fertilisers. As soon as they reach the first black spot, they stop and lick up the honey secreted by the gland, and then try to pass on to the next appendage above it. But the arrow-shaped barbs, turned back against the stem, block their further progress ; and even if they manage to squeeze themselves through with an effort, they are met just above by another honey-gland and another barrier in the shape of a second arrow-shaped ap- pendage. No ant ever gets beyond the third or 192 THE STORY OF THE PLANTS. fourth barricade; the device is efficient: the vetch thus offers blackmail to creeping thieves in the shape of stem-honey, in order to guard from their depredations the far more valuable and useful honey in the flowers, which is intended to attract the fertilising insects. When the purple flowers have in due time been fertilised, they produce long narrow pods, each containing about a dozen round pea-like seeds. As the pods ripen, the plant shrivels up, and usually dies away, leaving only the ripe seeds to represent its kind through the winter. But sometimes, in damp and luxuriant autumns, the stem struggles through the winter to a second season, and flowers again in the succeeding sum- mer. We express this fact as a rule by saying that the vetch is usually an annual, but occasion- ally a biennial. With most annuals, such as wheat or sunflower, the whole strength of the plant is used up in the production of seed ; and as soon as the seed is set, the plant dies immediately. Where annuals have the sexes on separate plants, however, the male plants die as soon as they have shed their pollen, their task being thus complete ; while the females live on till their seed has ripened. Common coltsfoot is another well-known plant whose life-history shows some points of great interest. It grows in the first instance from a feathery fruit, one-seeded and seed-like, which is carried by the wind, often from a great distance. These flying fruits alight at last upon some patch of bare or newly-turned soil, such as the bank of a stream where there has been lately a landslip, or the side of a railway cutting. These bare sit- uations alone suit the habits of the baby coltsfoot ; SOME PLANT BIOGRAPHIES. 193 if the fruit happens to settle on a light soil, al- ready thickly covered with luxuriant vegetation, it cannot compete against the established possess- ors. But the winged fruits, being dispersed on every side, enable many young plants to start well in life on the poor stiff clays which best suit the constitution of this riverside weed. The seed- ling grows fast in such circumstances, and soon produces large angular leaves, very broad and thick, which in the adult plant have often a di- ameter of five or six inches. They are green above, where they catch the sunlight and devour carbonic acid ; but underneath they are covered with a thick white wool, which is there for a cu- rious and interesting purpose. The damp clay valleys and river glens where coltsfoot lives by choice are filled till noon every day with mist and vapour; and heavy dew is deposited there every night through the summer season. Now, if this dew were allowed to clog the evaporation pores or stomata on the leaves of coltsfoot, the plant would not be able to raise water or proceed with its work except for perhaps a few hours daily. To prevent this misfortune, the under side of the leaves is thickly covered with a white coat of wool, on which no dew forms, and off which water rolls in little round drops, as you have seen it roll off a serge taole-cloth. By this ingenious device the coltsfoot manages tcK keep its evaporation pores dry and open, in spite of its damp and moisture- laden situation. One may say, indeed, that every point in the structure of every plant has thus some special purpose; indeed, one large object of the study of plants is to enable us to understand and explain such hidden purposes in the economy of nature. 194 THE STORY OF THE PLANTS. During its early life, once more, the young plant of coltsfoot is constantly engaged, like the whitlow-grass and the agave, in laying by mate- rial for its future flowering season. But it does not lay by, as they do, in its expanded leaves or other portions of its body visible above ground ; instead of that, it puts forth a creeping under- ground stem or root-stock, which pushes its way sideways through the tough clay soil, often for several feet, and sends up at intervals groups of large roundish leaves, such as I have already de- scribed, to w^ork above ground for it. You might easily take each such group for a separate plant, unless you dug up the root-stock and saw^ that they were really the scattered foliage of one sub- terranean stem, which grows horizontally instead of upward. During the summer the coltsfoot lays by in this buried root-stock quantities of rich ma- terial for next year's leaves and for its future flow r ers. In winter the leaves die down, and you see not a trace of the plant above ground. But in very early spring, as soon as the soil thaws, certain special buds begin to sprout on the under- ground stem, and send up tall naked scapes or flower-stems, usually growing in tufts together, and each crowned by a single large fluffy yellow flower-head. These stems are covered below by short purplish scales ; and their purple colouring matter enables them to catch and utilise to the utmost the scanty sunshine that falls upon the plant in chilly March weather. For this particu- lar colouring matter has the special property of converting the energy in rays of light into heat for warming the plant. The scape is also wrapped up in a sort of cottony wool, which helps to keep it warm; and the unopened flower-head turns SOME PLANT BIOGRAPHIES. 195 downward at first for still further safety against chill or injury. These various devices enable the coltsfoot to blossom earlier in the season than almost any other insect-fertilised flower, and so to monopolise the time and attention of the first flower-haunting March insects. Coltsfoot is a composite by family ; so its flowers are collected together into a head, after the ancestral fashion, and enclosed by an invo- lucre which closely resembles a calyx. But the type of flower-head differs somewhat from that in any of the composite plans I have hitherto described for you, because its outer florets are not flat and ray-shaped, but strap-like or needle- shaped. The inner florets, however, are bell- shaped, and much like those of the common daisy. The naked scapes, each resembling to the eye a shoot of asparagus, and .each crowned by a single fluffy yellow flower-head, are familiar objects on banks or railway cuttings in the first days of spring; I have known them open as early as the 1 2th of January, in sunny weather. But they grow entirely without leaves, and are produced at the expense of the material laid up in the underground stem by last season's foliage. They blossom, are fertilised, set their seeds, turn into heads of white feathery down, and produce ripe fruits which blow away and get dispersed, all before the leaves begin to appear at all above the soil. Thus you never can see the foliage and flowers together ; it is only by close observation that you can discover for yourself the connection between the heads of yellow flowers which come up in early spring, and the groups of large angular woolly leaves which follow them in the same spots much later in the season. 196 THE STORY OF THE PLANTS. The life-history of the coltsfoot introduces us also to another conception which we must clearly understand if we wish to know anything about many plant biographies. I have said already that parts of one and the same coltsfoot plant might easily be mistaken for separate individuals; and, indeed, if the stem gets severed, particular groups of leaves may live on as such, in two or more dis- tinct portions. This leads us on to the considera- tion of a great group of plants like the common wild strawberry, in which a regular system of sub- division exists, and in which new plants are ha- bitually produced by offsets or runners, as well as by seedlings. Such a method of increase is to some extent a survival into higher types of the primitive mode of reproduction by subdivision. A strawberry plant grows in the first instance from a seed, which was embedded in a carpel or seed-like fruitlet on the ripe red swollen receptacle which we commonly call a strawberry. This seed germinates, and produces a seedling, which puts forth small green leaves, divided into three leaflets each at the end of a long and slender leaf-stalk. As it grows older, however, besides its own tufted perennial stem or stock, it sends out on every side long branches or runners, which are in fact hori- zontal or creeping stems in search of new root- ing places. These stems run along the ground for some inches, and then root afresh. At each such rooting-point, the plant sends up a fresh bunch of leaves, which gradually grows into a distinct colony, by the decay of the intermediate portion or runner. Again, this new plant itself in turn sends forth runners in every direction all round it ; so that often the ground is covered for yards by a network of strawberry plants, all ulti- SOME PLANT BIOGRAPHIES. 197 mately derived from a single seedling. Theoret- ically, we must regard them all as severed parts of one and the same plant, accidentally divided from the main stem, since only the union of two different parents can give us a totally distinct in- dividual. But practically they are separate and independent plants, competing with one another thenceforth for food, soil, and sunshine. A great many plants are habitually propagated in such indirect ways, as well as by the normal method of flowering and seeding. Indeed, it is difficult to separate the two processes of mere growth, as shown in budding or branching, and reproduction by subdivision, as shown in the springing of saplings from the roots or stem, the production of runners, the division of bulbs, and the rooting of suckers. I will therefore give here a few select instances of these frequent incidents in the life-history of various species. The tiger-lilies of our gardens produce little dark buds, often called bulbils, in the angles of their foliage leaves. These buds at last fall off and root themselves in the soil, forming to all ap- pearance independent plants. Much the same thing happens with many English wild-flowers. For example, in the plant known as coral-root (allied to the cuckoo-flower) little bud-bulbs are formed in the angles of the leaves, which drop on the damp soil of the woods where the plant grows, and there develop into new individuals. In this last-named case the plant seldom sets its fruit at all, the reproduction being almost entirely carried on by means of the bulbils. Such instances sug- gest to us the pregnant idea that a seed is noth- ing more than a bud or young shoot, to whose making two separate parents have contributed. 198 THE STORY OF THE PLANTS. There is, in short, no essential difference between the two processes of growth and reproduction. Again, in the common lesser celandine the root- stock emits a large number of tiny pill-like tubers, which grow and lay by rich material underground (derived from the leaves) during the summer sea- son. In the succeeding spring, however, each of these tubers develops again into a separate plant, in a way with which the familiar instance of the potato has made us familiar. In the crocus, once more, and many other bulbous plants, sev- eral small bulbs are produced each year by the side of the large one, and these smaller bulbs are of course, strictly speaking, mere branches of the original crocus-stem. But they grow separate at last, by the decay or death of the central bulb, and themselves in turn produce at their side yet other bulbs, which become the centres of still newer families. We may parallel these cases with those of trees whose boughs bend down and root in the ground so as to become in time independ- ent individuals; or with runners like those of the strawberry and the creeping buttercup, which root and grow afresh into separate plantlets. Sometimes still more curious things happen to plants in the way of reproduction by subdivision. There is an English pondweed, for example, which grows in shallow pools liable to be frozen over in severe winters. As cold weather approaches, the top of the growing shoots in this particular pond- weed break off of themselves, much as leaves do at falling time. But they break off with all their living material still preserved w r ithin them undis- turbed; and they then sink and retire to the unfrozen depths of the pond, where they remain unhurt till spring comes round again. This is SOME PLANT BIOGRAPHIES. 199 just what the frogs and newts and other animal in- habitants of the pond do at the same time to pre- vent getting frozen. Next year the severed tops send out roots in the soft mud of the bottom, and grow up afresh into new green pondweeds. It is therefore impossible to make any broad line of distinction in this way between what may be considered as modes of individual persistence in the self-same plants, and what may be regarded as modes of reproduction by subdivision. Some plants, like couch-grass and elm, are almost always surrounded by young shoots which may ultimate- ly become to all intents and purposes independent individuals; while others, like corn -poppy or Scotch fir, never produce any offsets or suckers. In the meadow orchids each plant produces every summer a second tuber by the side of the old one; and from the top of this tuber the next year's stem arises in due time with its spike of flowers. Here we may fairly regard the tuber as a simple means of persistence in the plant itself ; there is nothing we could possibly call reproduc- tion. But in many lilies the older bulbs produce numerous small branch bulbs at their sides; and these younger bulbs may become practically in- dependent, each of them sending up in the course of time its own stem and its own spike of flowers. Even when the main trunk of a tree is dead, through sheer old age, it often happens, as in the elm and birch, that the roots send up fresh young shoots, which may grow again, and prolong the life of the plant indefinitely. In stone-crops and other succulent herbs, which grow in very dry and desert situations, the merest fragment of a stem, dropped on moist soil, will send out roots and grow afresh into a new individual. Cactuses and 200 THE STORY OF THE PLANTS. other desert plants have often to resist immense drought, and therefore possess extraordinary vital- ity in this way. They will grow again from the merest cut end under favourable conditions. These few short hints as to the life-history of various plants in different circumstances will serve to show you how vast is their variety. Every plant, indeed, has endless ways and tricks of its own ; and every point in its structure, however unob- trusive, has some purpose to serve in its domestic economy. Thus the ivy-leaved toad-flax, which grows on dry walls, has straight flower-stalks, which become bent or curved when the flowering is over. Why is this ? Well, the plant has ac- quired the habit of bending round its flower-stalk after the blossoming season, because it cannot sow its seeds on the bare stone, so it hunts about diligently for a crevice among the mortar into which it proceeds to insert its capsule, so that the seedlings may start fair in a fit and proper place for their due germination. So, too. the subterranean clover, growing on close-cropped hillocks much nibbled over by sheep, where its pods of rich seeds would be certainly devoured if exposed on a long stalk like that of other clovers, has developed a few abortive corkscrew- like blossoms in the centre of its flower-head, by whose aid the whole group of pods burrows its way spirally into the soil beneath ; so that the plant thus at once escapes its herbivorous ene- mies, and sows its own seed for itself automat- ically. It would be impossible in our space to do more than thus briefly indicate by two or three examples the immense number and variety of these special adaptations. Every plant has hun- dreds of them. There is not a tinv hair on the SOME PLANT BIOGRAPHIES. 2O1 surface of a flower, not a spot or a streak in the blade of a leaf, not a pit or depression on the skin of a seed, that has not its function. And close study of nature rewards us most of all for our trouble in this, that it reveals to us every day some delightful surprise, forces on our attention some hitherto unsuspected but romantic relation of structure and purpose. I will mention but one more case as a typical example. There exists as a rule a definite rela- tion between the shape and arrangement of the leaves in plants, and the shape and arrangement of the roots and rootlets, with regard to water- supply. Each plant, in point of fact, is like the roof of a house as respects the amount of rain which it catches and drains away ; and it is im- portant for each that it should utilise to the ut- most its own particular supply of drainage or rain water. Hence you will find that some plants, like the dock, have large channelled leaves, with a leaf- stalk traversed by a depression like a drainage runnel : plants of this type carry off all the water that falls upon them towards the centre, inwards. But such plants have always also a descending tap-root, which instantly catches and drinks up the water poured by the drainage system of the leaves towards the middle of the plant. In other plants, again, however, with round leaf-stalks and outward pointed leaves, the water that falls upon the foliage drains outward towards the circum- ference ; and in all such plants the roots, instead of descending straight down, are spreading and diffused, so as to go outward towards the point where the water drips on them. Moreover, in this latter case it is found, on digging up the plant carefully, that the absorbent tips of the 202 THE STORY OF THE PLANTS. rootlets are clustered thickest about the exact spots where the leaves habitually drop the water down upon them. Every plant is thus to some extent a catchment-basin which utilises its own rainfall : it collects rain for itself, and conducts it by a definite system of pipes and channels to the precise spots in the soil where it can best be sucked up for the plant's own purposes. On the other hand, while every part of every plant is thus minutely arranged for the common advantage, every species of plant and animal fights only for its own hand against all comers. Nature is therefore one vast theatre of plot and counterplot. The parasites prey on the vegeta- tive kinds; the vegetative kinds respond in turn by developing checks to counteract the parasites. The squirrels produce sharper and ever sharper teeth to gnaw through the nutshells; the nut- trees retaliate by producing for their part thicker and ever thicker shells to baffle the squirrels. And this play and by-play goes on unceasingly from generation to generation ; because only the cleverest squirrels can ever get enough nuts to live upon ; and only the hardest-shelled and bitterest-rinded nuts can escape the continual assaults of the squirrels. In order, therefore, really to understand the structure and life of any one species, we should have to know in the mi- nutest detail all about its native conditions, its soil, its surroundings, its allies, its hired friends, its blackmailing foes, its exterminating enemies. Such exhaustive knowledge of the tiniest weed is clearly impossible; but even the little episodes we can pick out piecemeal are full of romance, of charm, and of novelty. THE PAST HISTORY OF PLANTS. 203 CHAPTER XIV. THE PAST HISTORY OF PLANTS. I PROMISED some time since to return in due season to the question why plants, as a rule, ex- hibit distinct kinds or species, instead of merging gradually one into another by imperceptible de- grees. This problem is generally known as the problem of the origin of species. You might per- haps expect (since plants have grown and de- veloped, as we have seen, one out of the other) that they would consist at present of an unbroken series, each melting into each, from the highest to the lowest. This, however, is not really the case ; they form on the contrary groups of dis- tinct kinds : and the reason is, that natural selec- tion acts on the whole in the opposite direction. It tends to make plants group themselves into definite bodies or species, all alike within the body, and well marked off from all others outside it. Here is the way this arrangement comes about. As situations and circumstances vary, a form is at last arrived at in each situation which approximately fits the particular circumstances. This form may perhaps vary again in other situ- ations, and give rise to individuals better adapted to the second set of circumstances. But just in proportion as such individuals surpass in adap- tation one another will they live down the less adapted. Hence, the intermediate forms will tend to perish, and the world to be filled in the end with groups of plants, each distinct from others, and each relatively fixed and similar within its own limits. 204 THE STORY OF THE PLANTS. At all times, and in all places, this process of variation and adaptation is continually going on ; new kinds are being formed, and intermediates are dying out between them. For the interme- diates are necessarily less adapted than the older form to the old conditions, and than the newer form to the new ones. Moreover, when any great point of advantage is once gained by a kind, it tends to go on and be preserved, while variations in other parts con* tinue uninterrupted. Thus, the first composite plant (to take a concrete example) gained by the massing of its flowers into a compact head : and it then became a starting-point for fresh develop- ments, each of which maintained the massed flow- er-head, with its ring of united stamens, while adding to the type some fresh point of its own, which specially adapted it to a particular situ- ation. So, too, the first peaflower gained by the peculiar form of its oddly-shaped corolla, and therefore became the ancestor of many separate kinds, each of which retains the general pea-like type of blossom, while differing in other respects as widely from its neighbours as gorse and clo- ver, peas and laburnum, broom and vetches, scar- let-runners and lupines. A group of kinds, so de- rived from a common progenitor, but preserving throughout one or more of that progenitor's pe- culiarities, while differing much in other respects among themselves, is called a family. Thus we speak of the family of the peaflowers, the family of the roses, the family of the lilies, the family of the orchids. Each family may include several minor groups, known as genera (in the singular, a genus] ; and each such genus may further include several distinct kinds or species. THE PAST HISTORY OF PLANTS. 205 For example, all the peaflower/